D

daisy chain
In CICS intercommunication, the chain of sessions that results when a system requests a resource in a remote system, but the remote system discovers that the resource is in a third system and has itself to make a remote request.
DASD
See direct access storage device (DASD).
DASD sharing
An option that lets independent computer systems use common data on shared disk devices.
data aggregate
A group of data elements that describe a particular entity.
data availability
An IMS enhancement available with DBCTL. It allows PSB scheduling to complete successfully even if some of the full-function databases it requires are not available.
database (DB)
A collection of interrelated or independent data items stored together without redundancy to serve one or more applications.
Database Control (DBCTL)
An interface between CICS Transaction Server and IMS/ESA that allows access to IMS DL/I full-function databases and to data entry databases (DEDBs) from one or more CICS systems without the need for data sharing. It also provides release independence, virtual storage constraint relief, operational flexibility, and failure isolation.
database description (DBD)
The collection of macroparameter statements that define the characteristics of a database, such as the database's organization and access method, the segments and fields in a database record, and the relationship between types of segments.
database integrity
The protection of data items in a database while they are available to any application program. This includes the isolation of effects of concurrent updates to a database by two or more application programs.
database-level sharing
A kind of data sharing that enables application programs in one IMS subsystem to read data while another program in another IMS subsystem reads from the same database or updates it. In IMS data sharing, a CCS system can be an IMS subsystem. See also block-level data sharing.
database organization
The physical arrangement of related data on a storage device. DL/I database organizations are hierarchical direct (HD) and hierarchical sequential (HS).
database program communication block (DBPCB)
The PCB that describes an application program's interface to a database. One DBPCB is required for each database view used by the application program.
database record
In a DL/I, IMS or SQL/DS database, a collection of segments that contains one occurrence of the root segment type and all of its dependents arranged in a hierarchical sequence. It may be smaller than, equal to, or larger than the access method logical record.
database recovery
The function of restoring the user data sets, starting with a backup copy and applying all changes made to each data set after the backup was taken.
database recovery control (DBRC)
An IMS facility that maintains information needed for database recovery, generates recovery control statements, verifies recovery input, maintains a separate change log for database data sets, and supports the sharing of an IMS DL/I database by multiple subsystems. In IMS data sharing, a subsystem can be an IMS region or a CICS region.
database reorganization
The process of unloading and reloading a database to optimize physical segment adjacency, or to modify the DBD.
database resource adapter (DRA)
Component of the CICS-DBCTL interface in the CICS address space. Its functions include requesting connection and disconnection from DBCTL, telling CICS when a shutdown of DBCTL has been requested or if DBCTL has failed, managing threads, establishing contact with the DBCTL address space, and loading the DRA startup parameter table.
Data Cache Manager
A component of CICSPlex SM that manages logical cache storage for use by other CICSPlex SM components.
data-container
A named area of storage, maintained by BTS, and used to pass data between activities, or between different invocations of the same activity. Each data-container is associated with an activity; it is identified by its name and by the activity for which it is a container. An activity can have any number of containers, as long as they all have different names. See also process container.
data control block (DCB)
A control block used by access method routines in storing and retrieving data.
data definition name (ddname)
The name of a data definition (DD) statement that corresponds to a data control block that contains the same name.
data element
(1) A unit of data that, in certain context, is considered indivisible. For example, the data element "age of a person" with values consisting of all three-decimal digit combinations. (T)
(2) The smallest unit of data that can be referred to.
data entry database (DEDB)
A direct-access database that consists of one or more areas, with each area containing both root segments and dependent segments. The database is accessed using VSAM media manager.
data independence
In CICS, the ability to request data by a high-level data-management method without concern as to how the data is stored or retrieved.
data interchange block (DIB)
A block created by the CICS data interchange program (DIP) to control input and output to SNA batch devices. The DIB is chained to the appropriate TCTTE for the batch device, and is released at the termination of the transaction.
data interchange program (DIP)
A CICS program that communicates with batch data interchange terminals, such as the 3790, for bulk transfer of dumps, data sets, and so on.
Data Interfile Transfer, Testing and Operations (DITTO) utility
An IBM licensed program that provides file-to-file services for card I/O, tape, and disk devices.
Data Language/I (DL/I)
The IMS data manipulation language, a common high-level interface between a user application and IMS. DL/I calls are invoked from application programs written in languages such as PL/I, COBOL, VS Pascal, C, and Ada. It can also be invoked from assembler language application programs by subroutine calls. IMS lets the user define data structures, relate structures to the application, load structures, and reorganize structures.
data link protocol
In SNA, a set of rules for data communication over a data link in terms of a transmission code, a transmission mode, and control and recovery procedures.
data management block (DMB)
An IMS control block in main storage that describes and controls a physical database. It is constructed from information obtained from the ACB library or the DBD library.
data-owning region (DOR)
A CICS address space whose primary purpose is to manage files and databases. See application-owning region (AOR), and terminal-owning region (TOR).
data repository
A component of CICSPlex SM that provides methods for creating, accessing, updating, and deleting data in the CICSPlex SM data repository.
data security
The protection of data against unauthorized disclosure, transfer, modification, or destruction, whether accidental or intentional.
data set
The major unit of data storage and retrieval, consisting of a collection of data in one of several prescribed arrangements, and described by control information to which the system has access.
data set name block (DSNAME block, DSNB)
An area, addressed by a FCT entry, that represents a physical VSAM or BDAM (DAM in CICS/VSE) data set that is being accessed through one or more CICS files. A DSNAME block (DSNB) is created, if it does not already exist, when a file is opened or, in CICS Transaction Server only, when a SET FILE DSNAME command is executed.
data set name sharing
An MVS or VSE option that allows one set of control blocks to be used for the base and the path in a VSAM alternate index.
data set profile
A RACF profile that provides protection for one or more data sets. The information in the profile can include the data set profile name, profile owner, universal access authority, access list, and other data. See profile, discrete profile and generic profile.
data space
A range of up to two gigabytes of contiguous virtual storage addresses that a program can directly manipulate. Unlike an address space, a data space can hold only data; it does not contain common areas or system data or programs. See also address space.
data stream
All information (data and control commands) sent over a data link usually in a single read or write operation. For example, a data stream is used to send displays and to receive displays from a workstation device.
data table
A file whose records are held in main storage. See also CICS-maintained data table (CMT) and user-maintained data table (UMT).
DB
See database.
DB2
A family of IBM licensed programs for relational database management.
DBCS
See double-byte character set (DBCS).
DBCTL
See Database Control (DBCTL).
DBD
See database description (DBD).
DBO
See DL/I backout table (DBO).
DBPCB
See database program communication block (DBPCB).
DBRC
See database recovery control (DBRC).
DCB
See data control block (DCB).
DDEP
Direct dependent segment in a DEDB.
DDIR
See DL/I database directory (DDIR).
DDMMYYYY
Day-day-month-month-year-year format of a date (for example, 14022001 for 14 February 2001). This is the default format for the DATFORM system initialization parameter.
ddname
See data definition name (ddname).
deadlock
(1) Unresolved contention for the use of a resource.
(2) An error condition in which processing cannot continue because each of two elements of the process is waiting for an action by, or a response from, the other.
deblocking
The process of removing each logical record from a block. See also blocking.
debugging client
A program that runs on a workstation and is used to debug a CICS application program.
debugging profile
Data that specifies a set of application programs which are to be debugged together. See also profile.
DEDB
See data entry database (DEDB).
default group
In RACF, the group specified in a user profile that is the default current connect group.
default user
The user whose security attributes are used to protect CICS resources in the absence of other, more specific, user identification. For example, except in the case of terminals defined with preset security, the security attributes of the default user are assigned to terminal users who do not sign on.
default user ID
The user identifier (userid) of the default user. The default user ID is specified with the DFLTUSER system initialization parameter.
deferred work element (DWE)
A work element created and placed on a chain (the DWE chain) to save information about an event that must be completed before task termination but that is not completed at the present time. DWEs are also used to save information about work to be backed out in case of an abend.
defined userid
A user identifier (userid) named on a DEFINE PROCESS or DEFINE ACTIVITY command. It specifies the userid under whose authority the process or activity will be run, if it is activated by a RUN command. If the process or activity is activated by a LINK command, it runs under the authority of the userid of the transaction that issues the LINK.
define the file (DTF)
The DTF is a DAM control block that identifies to DAM the file associated with this DAM request. It is passed to DAM by DFHFCD to initiate a DAM request, and lasts for the lifetime of the CICS run. The DTF is included in the associated FCT entry, and is generated at FCT assembly time by the DTFDA macro. There is one DTF per DAM FCT entry.
definite response (DR)
In SNA, a value in the response-requested field of the request header that directs the receiver of the request to return a response unconditionally, whether positive or negative, to that request. See also exception response (EX, ER), no response.
delegation
In RACF, the act of giving other users or groups authorities to perform RACF operations.
delete lock
Lock acquired by CICS file control whenever a DELETE, WRITE, or WRITE MASSINSERT operation is being performed for a recoverable VSAM KSDS or a recoverable path over a KSDS.
dependent default
Attribute value for RDO that differs depending on the values for the other attributes that have already been specified on the command line.
dependent region
In a multi-MVS or VSE MRO XRF configuration, a region that receives commands from a master or coordinator region at takeover time. It cannot initiate a takeover.
deployed JAR file
A generic term for a file produced from the ejb-jar file. It contains the XML deployment descriptor and enterprise bean classes from the ejb-jar file, plus additional classes generated to support the chosen EJB container. See also CICS-deployed JAR file.
deployed security role
A security role that is qualified with the display name specified in an enterprise bean's deployment descriptor, and the prefix specified in the EJBROLEPRFX system initialization parameter. See security role and deployment descriptor. For more information see Java(TM) applications in CICS.
deployment
The act of packaging enterprise beans into a JAR file for distribution to a container on an enterprise bean server.
deployment descriptor
An XML file that describes how a module or application should be deployed, by specifying configuration and container options. For example, an EJB deployment descriptor passes information to an EJB container about how to manage and control an enterprise bean. See also deployed security role.
destination
A queue of data used with the CICS transient data facility.
destination control table
A table describing each of the transient data destinations used in CICS. This table contains an entry for each extrapartition, intrapartition, and indirect destination.
device dependence
The reliance on the characteristics of particular types of devices used in writing and running programs or in performing functions. See also device independence.
device independence
The capability to write and run programs or perform functions without regard for the physical characteristics of devices. See also device dependence.
device message handler (DMH)
For CICS with TCAM SNA, the logical unit in SNA terms. All data flow, control, session startup and takedown, and response handling are provided in the DMH.
DFH
Three-character prefix of all CICS modules.
DIB
See data interchange block (DIB) and DL/I interface block (DIB).
dictionary data section
One of the data sections of a CICS monitoring record written to SMF. The dictionary data section defines all the performance data that is being gathered or can be gathered during this CICS run.
DIP
See data interchange program (DIP).
direct access
A method for retrieval or storage of a VSAM data record that is independent of the record's location relative to the previously retrieved or stored data. See also sequential access.
direct access method
An access method used to retrieve or update particular blocks of a data set on a direct access device.
direct access storage device (DASD)
A storage device that provides direct access to data.
directory manager domain
A CICS domain that provides resource-table lookup services for CICS Transaction Server for z/OS components such as transaction manager, program manager, and user domains. The resource definitions for which the directory manager domain provides services are transaction definitions, remote transaction definitions, transaction classes, TPNames, user attributes, programs, BMS mapsets, and BMS partition sets.
dirty read
A read request that does not involve any locking mechanism, and which may obtain invalid data - that is, data that has been updated, but is not yet committed, by another task. This could also apply to data that is about to be updated, and which will be invalid by the time the reading task has completed.See also read integrity.
discrete profile
A resource profile that can provide RACF protection for only a single resource. For example, a discrete profile can protect only a single data set or minidisk. See also data set profile, generic profile, resource profile.
DISOSS
See Distributed Office Support System (DISOSS).
dispatch
(1) To allocate processing time on a specific device for a job that is ready to run.
(2) In CICS, to schedule a task for execution. Dispatching is done by CICS task control. See also service request block (SRB).
dispatcher domain
Major component of CICS concerned with attaching, running, and detaching tasks and scheduling task control blocks for the various modes: quasi reentrant, resource-owning, or concurrent.
dispatching priority
A number assigned to tasks, used to determine the order in which they are to use the processor in the CICS multitasking environment.
disposition
A means of indicating to VSE/POWER how job input and output is to be handled. A job may, for example, be deleted or kept after processing.
distributed application
An application whose component programs run on two or more CICS regions.
distributed data
Data that is stored on more than one system and is available to remote users and application programs.
Distributed Office Support System (DISOSS)
An IBM office systems product that helps CICS form the hub for storage, retrieval, and forwarding of documents among various office systems products.
distributed processing
Processing in which resources or functions are dispersed among two or more interconnected processors, typically over a network.
Distributed Processing Control Executive (DPCX)
An IBM licensed program that controls the IBM 8100 Information System.
distributed program link (DPL)
A function of CICS intersystem communication that enables an application program to ship LINK requests to another application program on a different instance of CICS.
distributed routing model
A "peer-to-peer" dynamic routing system, in which each of the participating CICS regions can be both a routing region and a target region. The distributed routing model is implemented by the distributed routing program.
distributed routing program
A CICS-supplied user-replaceable program that can be used to dynamically route; BTS processes and activities, and Transactions started by non-terminal-related EXEC CICS START commands.
distributed transaction processing (DTP)
A process that enables a CICS transaction to communicate synchronously with a transaction running in another instance of CICS.
distributed unit of work (DUW)
In a distributed process, all processing between two syncpoints taken by two or more intercommunicating transactions using a two-phase commit protocol. A DUW is a distributed LUW.
distribution zone
In SMP/E, a group of VSAM records that describe the structure and contents (that is, the SYSMODs and elements) of a set of distribution libraries.
DITTO utility
See Data Interfile Transfer, Testing and Operations.
DJAR
A CICS resource definition that defines a CICS-deployed JAR file. It is not a deployed JAR file itself.
DLBL statement
Data definition statement in VSE JCL. A DLBL statement specifies the name and characteristics of a data set to be associated with a file definition in the FCT. The name of the DLBL statement is the same as the name of the file definition.
DL/I
See Data Language/I (DL/I).
DL/I backout table (DBO)
In the restart data set, a summary table that contains an entry for each in-flight task that was scheduled to alter a local DL/I database. Data in this table is available to user-written exit programs.
DL/I database directory (DDIR)
List of data management blocks (DMBs) that define for DL/I the physical and logical characteristics of databases.
DL/I interface block (DIB)
A block containing variables automatically defined in an application program using HLPI to receive information passed to the program by DL/I during execution. A block automatically inserted into a program by the DLI command translator. Whenever a program issues an EXEC DLI request, DLI responds by storing information in the DIB.
DLISAS
See DLI separate address space (DLISAS).
DLI separate address space (DLISAS)
A component of DBCTL that resides in the IMS address space. It is a separate address space that contains DL/I code, control blocks, buffers for DL/I databases and program isolation. See CICS-IMS DBCTL environmentfor more information.
DMB
See data management block (DMB).
DMH
See device message handler (DMH).
document
A logical structure that a CICS transaction can use to manipulate text or other structured information. For more information, see CICS Application Programming Guide.
document template
A unit of information that is used to construct a document. A document template can contain fixed text, and symbols that represent text whose value is supplied by an application program. Document templates can be created by a CICS application, or retrieved from an external source. For more information, see CICS Application Programming Guide.
domain
A functionally isolated area of the CICS system that owns resources to which it has sole access and that communicates with other parts of CICS through strictly defined interfaces called gates.
domain gate
An entry point or interface to a CICS domain. A domain gate can be called by any authorized caller who needs to use some function provided by the domain.
domain manager domain
Major component of CICS responsible for maintaining, through the use of catalog services, permanent information about individual domains.
Domain Name System (DNS)
In the Internet suite of protocols, the distributed database system used to map domain names to IP addresses.
DOR
See data-owning region (DOR).
double-byte character set (DBCS)
A set of characters in which each character is represented by two bytes. These character sets are commonly used by national languages, such as Japanese and Chinese, that have more symbols than can be represented by a single byte. See also single-byte character set.
DPCX
See Distributed Processing Control Executive (DPCX).
DPL
See distributed program link (DPL).
DR
See definite response (DR).
DRA
See database resource adapter (DRA).
DRA control exit
Enables the DRA to pass information from itself and DBCTL independently of CICS. It is invoked whenever the DRA needs to determine whether to continue processing.
DRA startup parameter table
Provides the parameters needed to define a DBCTL subsystem.
DRx response
See definite response (DR).
DSA
See dynamic storage area (DSA).
DSNAME block
See data set name block (DSNAME block or DSNB).
DSNB
See data set name block (DSNAME block or DSNB).
DTB
See dynamic transaction backout (DTB).
DTF
See define the file (DTF).
DTP
See distributed transaction processing (DTP).
DTR
See dynamic transaction routing (DTR).
dual-purpose definition
For transaction routing or function shipping, a means of sharing file, terminal, or transaction definitions between systems. For further information, see Dual-purpose resource definition for transient data.
dual-screen
Running EDF and the transaction to be tested on different terminals.
dump
A representation of the contents of selected areas of main storage used to find out whether a program is functioning as intended and to analyze problems. Dumps may be recorded by CICS either as a consequence of failure detected during CICS execution, or upon explicit request. See also partition dump, system dump (IDUMP), and transaction dump.
dump code
(1) In CICS Transaction Server, a predefined name by which a dump is known. There are two types of dump code, transaction dump codes and system dump codes, used in transaction dumps and system dumps, respectively. A dump code can be defined by CICS or the user and is used to select a set of system actions. These actions are held in either the system or transaction dump table See also system dump code, system dump table entry, transaction dump code, transaction dump table (TDT).
(2) In CICS/VSE, a predefined name by which a transaction dump is known. The VSE/ESA Messages and Codes manual contains a description of the transaction dump codes defined by CICS.
dump data set
A sequential data set (optional) used to record dumps of transactions (tasks) within the system. It can be formatted and printed by the CICS dump utility program (DFHDUP). If required, the user can define two dump data sets (DFHDMPA and DFHDMPB), switching between them during online execution of CICS.
dump domain
Major component of CICS responsible for producing storage dumps and for handling the associated data sets and dump tables.
dump table
A table of dump codes to enable a user to vary the system actions taken when a dump is produced for a particular dump code. There are two dump tables - one containing system dump codes for system dump requests, and one containing transaction dump codes for transaction dump requests. Dump tables are internally maintained by CICS, but cannot be externally generated like CICS control tables. There are two dump tables - one containing system dump codes for system dump requests, and one containing transaction dump codes for transaction dump requests. Dump tables are internally maintained by CICS, but cannot be externally generated like CICS control tables.
dump utility program (DFHDUP)
An offline utility program that formats and prints the output from formatted dump, and prints transaction dumps. It operates in batch mode and, for formatted dumps, identifies each storage area, program, and table entry, and prints them separately, with actual and relative addresses.
durability
After a transaction completes successfully (commits), its changes to the state survive failures. See also ACID properties.
DUW
See distributed unit of work (DUW).
DWE
See deferred work element (DWE).
dynamic allocation
Facility of IMS Version 2.2 (or later) and of CICS Transaction Server, for allocating DL/I databases and CICS file control data sets, respectively. If no DD statement is provided for the database data sets contained in the database, allocation happens automatically when the database is scheduled.
dynamically loaded program
Program loaded into a dynamic storage area as required by a task.
dynamic backout
A process that automatically cancels all activities performed by an application program that terminates abnormally. See also backout and syncpoint.
dynamic buffer
Used to store backout information in the dynamic log for dynamic transaction backout (DTB) purposes. The dynamic buffer is not acquired until a recoverable resource has been modified. If dynamic backout is not defined for a transaction, the dynamic buffer is not used.
dynamic log
An area in main storage used (by the journal control program) for storing copies of all changes to recoverable resources that might be required for dynamic backout of an LUW. Every execution of a transaction that has dynamic transaction backout specified has an associated dynamic log area.
dynamic parse
A method of parsing TSO commands according to syntax given in an external file.
dynamic partition
A partition configured at the time of program execution according to the storage requirements of the application program or program to which the partition is allocated.
dynamic partition balancing
A VSE facility that allows the user to specify that two or more or all partitions of the system should receive about the same amount of time on the processing unit.
dynamic routing
The automatic routing of a transaction or program, at the time it is initiated, from a requesting region to a suitable target region. Routing terminal data to an alternative transaction at the time the transaction is invoked. To do this, CICS allows the dynamic routing program to intercept the terminal data and redirect it to any system and transaction it chooses.
dynamic routing model
The "traditional", hierarchical CICS dynamic routing system, in which a single terminal-owning region (the routing region) routes transactions between several application-owning regions (the target regions). The dynamic routing model is implemented by the dynamic routing program.
dynamic routing program
A user-replaceable CICS program that selects dynamically both the system to which a request is to be sent and the transaction's remote name. The alternative to using this program is to make these selections when a remote transaction is defined to CICS (static routing).
dynamic storage
An area of storage that is explicitly allocated by a program or procedure while it is running. See also auxiliary storage.
dynamic storage area (DSA)
In CICS Transaction Server, there are five dynamic storage areas. These are CICS and user areas below the 16MB line, CICS and user above the 16MB line, and an extended read only area above the 16MB line. CICS DSAs are preallocated at system initialization. CICS DSAs are preallocated at system initialization as specified by a series of system initialization parameters, CDSASZE, UDSASZE, ECDSASZE, ERDSASZE, and EUDSASZE.
dynamic transaction backout (DTB)
The process of canceling changes made by a transaction to recoverable resources following a failure of the transaction for whatever reason.
dynamic transaction routing (DTR)
The automatic routing of a transaction, at the time it is initiated, from a transaction-owning region (TOR) to a suitable application-owning region (AOR).
dynamic transaction routing program (DFHDYP)
A user-replaceable CICS program that selects dynamically both the system to which a transaction routing request is to be sent and the transaction's remote name. The alternative to using this program is to make these selections when a remote transaction is defined to CICS (static transaction routing). For programming information, see Writing a dynamic routing program.
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