M

macro
An instruction that when executed causes the execution of a predefined sequence of instructions in the source language. The predefined sequence can be modified by parameters in the macro. CICS RDM macros are assembler macros and are converted by the assembler.
macro temporary store (MTS)
The SMP/E data set used to hold updated versions of macros that will not be placed in a target system library. They are stored during APPLY processing and deleted by ACCEPT or STORE processing.
main storage
(ISO) Program-addressable storage from which instructions and data can be loaded directly into registers for subsequent execution or processing.
main storage database (MSDB)
In IMS, a root-segment database that resides in main storage and that can be accessed to a field level.
maintain system history program (MSHP)
A program used for automating and controlling various installation, tailoring, and service activities for a VSE system.
maintenance point
A CICSPlex SM address space (CMAS) that is responsible for maintaining CICSPlex SM definitions in its data repository and distributing them to other CMASs involved in the management of a CICSplex.
major object descriptor block (MODB)
In CICSPlex SM, a control structure built by Kernel Linkage during initialization of a CICSPlex SM component that contains a directory of all methods that make up that component. The structure of the MODB is the same for all components.
major object environment block (MOEB)
In CICSPlex SM, a control structure built by Kernel Linkage during initialization of a CICSPlex SM component and pointed to by the MODB. MOEB stores information critical to a CICSPlex SM component and anchors data used by the component. The structure of the MOEB is unique to the component it supports.
map
In BMS, a format established for a page or a portion of a page, or a set of screen format descriptions. A map relates program variables to the positions in which their values appear on a display device. A map contains other formatting information such as field attributes. A map describes constant fields and their position on the display, the format of input and output fields, the attributes of constant and variable fields, and the symbolic names of variable fields.
map definition
Definition of the size, shape, position, potential content, and properties of BMS map sets, maps, and fields within maps, by means of macros. See also map set definition macro (DFHMSD), map definition macro (DFHMDI), and field definition macro (DFHMDF).
map definition macro (DFHMDI)
In BMS, a macro that defines a map within the map set defined by the previous DFHMSD macro. map set definition macro (DFHMSD), and field definition macro (DFHMDF).
mapped conversation
In advanced program-to-program communications (APPC), a temporary connection between an application program and an APPC session in which the system provides all the information on how the data is formatted. See also basic conversation.
mapping
In BMS, the process of transforming field data to and from its displayable form.
map set
In basic mapping support (BMS), one or more maps combined in a map set. The effects of this combination are to reduce the number of entries in the PPT, and to load simultaneously all maps needed for one application.
map set definition macro (DFHMSD)
A macro that is used to define a set of BMS maps. See also Defining The Map Set.
map set suffix
In BMS, a suffix relating different versions of a map set to different terminal models or partitions. This allows you to format the same data differently on different screen types, in response to the same programming request.
master
In a multi-MVS or VSE MRO XRF configuration, a region that issues commands to dependent regions at takeover time. See also coordinator.
master JVM
A JVM that initializes and owns the shared class cache. The master JVM externalizes its system heap to become the shared class cache, and supplies the class loading paths needed to load classes into it. The master JVM is not used to run applications.
master terminal
(1) The IMS logical terminal that has complete control of IMS resources during online operations.
(2) In CICS, the terminal at which a designated operator is signed on.
master terminal functions
A set of functions that allow a user to dynamically control and alter the operation of a CICS system.
master terminal operator
Any CICS operator authorized to use the master terminal functions transaction (CEMT).
MBO
See message backout table (MBO).
MCP
See message control program (MCP).
MCT
See monitoring control table (MCT).
MDT
See modified data tag (MDT).
message area
In BMS, the area of a screen used to send instruction messages to assist the operator in processing a transaction. This area should be separate from the application data area to allow communication with the operator, without disturbing the application data. The message area is normally the bottom one or two lines of the screen.
message backout table (MBO)
In the restart data set, a summary table that contains an entry for each terminal for which logged or journaled message or message resynchronization records were written to the restart data set. Data in this table is available to user-written exit programs.
message cache
A temporary storage queue with a DATAID of DFHMxxxx, where xxxx is the identification of a logical unit, into which CICS reads messages (for message-protected tasks only) during emergency restart. A user-written enquiry program run after emergency restart can read the contents of message caches. CICS does not read or purge message caches.
message control program (MCP)
In ACF/TCAM, a specific implementation of an access method, including I/O routines, buffering routines, activation and deactivation routines, service facilities, and SNA support.
message data set
The message data set is used principally to pass messages about the current state of specific resources from the active system to the alternate system. It is also used for the secondary surveillance signals of the active, alternate, or both CICS systems, when the control data set is unavailable for this purpose, either because the last write has not completed yet or because of I/O errors.
message domain
Major component of CICS. It is a repository for CICS messages and it handles the sending of messages to transient data destinations or to the console. It also provides an interface for returning the text of a message to the caller.
message performance option
The improvement of ISC performance by eliminating syncpoint coordination between the connected systems.
message protection
A recovery and restart function provided by CICS. It logs input and output messages for VTAM terminals and enables the messages to be recovered following a system failure.
message routing
A method used for building a logical message and routing it to one or more terminals. The message is scheduled, for each designated terminal, to be delivered as soon as the terminal is available to receive messages, or at a specified time. Terminal operators who receive the message use terminal operator paging commands to view it. A variety of operands on the ROUTE command allow you flexibility when specifying the message destinations.
message switching
The process of receiving a message, storing it, and forwarding it to its destination unaltered.
Meta-Object Facility (MOF)
A standard for the definition of information models and the subsequent mapping of these models to CORBA interfaces.
mirror task
CICS task that services incoming requests that specify a CICS mirror transaction (CSMI, CSM1, CSM2, CSM3, CSM5, CPMI, CVMI, or a user-defined mirror transaction identifier). For more information, see The Mirror Transaction & Transformer Program.
mirror transaction
CICS transaction that recreates a request that is function shipped from one system to another, issues the request on the second system, and passes the acquired data back to the first system.
mismatch
The situation when CICS assigns an available TCB from the open TCB pool, the HP TCB pool or the JVM pool to a request, when the TCB has the correct mode (J8, J9, H8 or L8) but the wrong attributes (for example, a different program name or JVM profile from that specified by the request). The TCB can be reused but its attributes must be changed. For J8 and J9 TCBs, this means that the JVM must be re-initialized. See also steal.
mixed traffic
A function of the VTAM class of service facility. Different kinds of traffic can be assigned to the same virtual route, and, by selecting appropriate transmission priorities, undue session interference can be prevented.
MLPA
See modified link pack area (MLPA).
MMDDYYYY (mmddyyyy)
Month-month-day-day-year-year format of a date (for example 04281934 for 28 April 1934). This format can be specified in the DATFORM system initialization parameter. For more information, see Specifying CICS system initialization parameters.
MODB
See Major object descriptor block (MODB).
mode
(1) In SNA data communications, the set of rules and protocols to be used for a session. See also session.
(2) The processing state of an activity. An activity can be in an initial, active, dormant (that is, waiting for an event), cancelling, or complete mode.
modegroup
A VTAM LOGMODE entry, which can specify (among other things) the class of service required for a group of APPC sessions.
modename
The name of a modeset and of the corresponding modegroup.
modeset
In CICS, a group of APPC sessions. A modeset is linked by its modename to a modegroup (VTAM LOGMODE entry) that defines the class of service for the modeset.
modified data tag (MDT)
(1) An indicator, associated with each input or output field in a displayed record, that is automatically set on when data is typed into the field. The modified data tag is maintained by the display file and can be used by the program using the file.
(2) In the attribute byte of each field in a BMS map, a bit that determines whether the field should be transmitted on a READ MODIFIED command (the command used by CICS for all except copy operations).
modified link pack area (MLPA)
An element of MVS/ESA virtual storage. This area provides a temporary extension to the PLPA existing only for the life of the current IPL. You can use this area to add or replace altered LPA-eligible modules without having to recreate the LPA. See also pageable link pack area (PLPA).
MOEB
See Major object environment block (MOEB).
MOF
See Meta-Object Facility
monitor
A user-provided program that handles unexpected events reported by FEPI.
monitoring
(1) The regular assessment of an ongoing production system against defined thresholds to check that the system is operating correctly. See also monitoring domain.
(2) Running a hardware or software tool to measure the performance characteristics of a system.
(3) Pertaining to the collection of performance data for all user- and CICS-supplied transactions during online processing for later offline analysis.
monitoring control table (MCT)
A CICS table for the exclusive use of, in CICS Transaction Server, the monitoring domain, and in CICS/VSE, the monitoring facility. The MCT contains definitions of user event monitoring points (EMPs). EMPs describe how user data fields in the performance class records are to be manipulated at each user EMP. See also event monitoring point (EMP).
monitoring domain
In CICS Transaction Server only, the CICS domain responsible for producing performance information on each task. Note that CICS distinguishes between monitoring and statistics, but IMS does not. See also monitoring.
monitoring record
Any of three types of task-related activity record (performance, event, and exception) built by the CICS monitoring domain in CICS Transaction Server. Monitoring records are available to the user for accounting, tuning, and capacity planning purposes. See The classes of monitoring data: Overview for a description of the three types of account class data that can be collected. See also performance class data. exception class data, and SYSEVENT class data.
monitoring section descriptor
The section descriptor preceding each section of monitoring data written to the journal file, and built at the beginning of each monitoring buffer.
monitoring section prefix
A prefix that precedes each section of monitoring data written to the journal. It is built in an area immediately after the journal control area (JCA). CICS moves it to the journal buffer immediately before the section descriptor.
MRO
See multiregion operation (MRO).
MSDB
See main storage database (MSDB).
MSHP
See maintain system history program (MSHP).
MTS
See macro temporary store (MTS).
multi-MVS environment
A physical processing system that is capable of operating more than one MVS image. See also MVS image
multiple mirror situation
A transaction condition that can arise in an intercommunication environment. When a transaction accesses resources in more that one remote system, the intercommunication component of CICS invokes a mirror transaction in each system to execute requests for the application program. When the application program reaches a syncpoint, the intercommunication component exchanges syncpoint messages with those mirror transactions that have not yet terminated (if any).
Multiple Virtual Storage (MVS)
The primary operating system used on IBM mainframes. This operating system manages large amounts of memory and disk space.
Multiple Virtual Storage/Enterprise Systems Architecture (MVS/ESA)
Renamed, and more commonly known as z/OS.
multiprogramming
The concurrent execution of two or more computer programs by a computer.
multiregion operation (MRO)
Communication between CICS systems in the same processor without the use of SNA network facilities. This allows several CICS systems in different regions to communicate with each other, and to share resources such as files, terminals, temporary storage, and so on. The systems must be in the same operating system; or, if the XCF access method is used, in the same MVS sysplex. See also intersystem communication (ISC) and CICSplex.
multitasking (tasking)
A mode of operation that provides for concurrent performance or interleaved execution of two or more tasks.
multithreading
Use, by several transactions, of a single copy of an application program. See also single threading.
MVS
See Multiple Virtual Storage (MVS).
MVS/Data Facility Product (MVS/DFP)
A major element of MVS, including data access methods and data administration utilities.
MVS/DFP
See MVS/DFP.
MVS/ESA
See Multiple Virtual Storage/Enterprise Systems Architeture (MVS/ESA).
MVS/ESA extended nucleus
A major element of MVS/ESA virtual storage. This area duplicates the MVS/ESA nucleus above the 16MB line. See also MVS/ESA nucleus.
MVS/ESA nucleus
A major element of MVS/ESA virtual storage. This static storage area contains control programs and key control blocks. The area includes the nucleus load module and is of variable size, depending on the installation's configuration. The nucleus is duplicated above the 16MB line as the MVS/ESA extended nucleus.
MVS image
A single occurrence of the MVS/ESA operating system that has the ability to process work. See also multi-MVS environment, single-MVS environment.
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