The type of initialization that CICS® performs is not only determined by the START parameter. The CICS local and global catalogs also play a major role in the initialization process, together with any system initialization parameters that you provide, either in the SIT or at run time by one of the three methods described in Using system initialization control keywords..
CICS uses its catalogs to save information between CICS shutdown and the next restart.
CICS uses the global catalog to save all resource definitions that are installed at CICS shutdown. These are:
The resource definitions that CICS saves at its shutdown may have been installed during a cold start (from a list of groups specified by a group list system initialization parameter), or during CICS execution (by RDO commands).
If you run CICS with START=AUTO, and a warm or emergency restart results, CICS restores all the installed resource definitions as they were at normal CICS shutdown, or at the time of system failure. The general rule is that you cannot alter installed resource definitions during a restart except by coding START=COLD or START=INITIAL. For details of the results of the possible combinations of CICS restart-type and global catalog state, see The START system initialization parameter.
The CICS domains also use the global catalog to save their domain status between runs. In some cases this information can be overridden during a restart by supplying system initialization parameters. For example, CICS monitoring uses the cataloged status at a restart, but modified by any system initialization parameter In other cases the domain information saved in the catalog is always used in a restart. For example, CICS statistics interval time is always restored from the catalog in a warm or emergency restart, because the statistics domain does not have this as a system initialization parameter. To change this you must use CEMT or EXEC CICS commands after control is given to CICS. Alternatively, you can enforce system defaults by performing a cold start.
The CICS domains use the local catalog to save some of their information between CICS runs. If you delete and redefine the local catalog, you must:
For more information about initializing the local catalog, see Defining the local catalog. Some of the information that is saved in the local catalog can be overridden at CICS system initialization by system initialization parameters, such as CICS transaction dump data set status.
You can influence the type of startup that CICS performs, by specifying the START system initialization parameter, as follows:
Depending on whether either or both of these records exist, and their contents, CICS decides which type of start to perform:
If you set CICS to perform an initial start, you should reinitialize the local catalog before bringing up CICS.
Log records for local resources are purged and resource definitions rebuilt from the CSD or CICS control tables. Units of work on other systems are resynchronized with this system, as described under START=COLD.
For the warm restart to be successful, the local catalog must contain the information saved by the CICS domains during the previous execution.
A warm start restores CICS to the state it was in at the previous shutdown.
You can modify a warm restart by coding the NEWSIT system initialization parameter. This has the effect of enforcing the system initialization parameters coded in the SIT, overriding any cataloged status from the previous CICS shutdown.
The exceptions to this is the system initialization parameter FCT, the CSDxxxxx group (for example CSDACC), and GRPLIST, which are always ignored in a warm restart, even if you specify NEWSIT=YES. Specifying NEWSIT=YES causes, in effect, a partial cold start.
START=AUTO should be the normal mode of operation, with the choice of start being made by CICS automatically. Use the recovery manager utility program, DFHRMUTL, to set overrides.
You should rarely need to specify START=INITIAL; if you simply want to reinstall definitions of local resources from the CSD, use START=COLD instead.
Examples of times when an initial start is necessary are:
If it is necessary to perform an initial start of CICS, you can do so in two ways:
Recovery information relating to remote systems or to RMI-connected resource managers is preserved. The CICS log is scanned during startup, and any information regarding unit of work obligations to remote systems, or to non-CICS resource managers (such as DB2®) connected through the RMI, is preserved. (That is, any decisions about the outcome of local UOWs, needed to allow remote systems or RMI resource managers to resynchronize their resources, are preserved.)
Note that, on a cold start, the following are not preserved:
A start initiated by START=COLD is not entirely without reference to the previous run of a CICS system using the same global catalog. If you want to perform a fully cold start of CICS, without reference to any previous execution, code START=INITIAL. If you simply want to reinstall definitions of local resources from the CSD, use START=COLD.
There may be times when it is necessary to perform a cold start of CICS, irrespective of the type of system termination that CICS recorded in the global catalog. You can do this in two ways:
When it takes over, the alternate CICS region becomes the active CICS region.
The effect of specifying START=STANDBY on the alternate CICS region is similar to that of the START=AUTO option.
If you code START=STANDBY with XRF=NO, initialization fails with message DFHXA6530, and CICS terminates abnormally with a dump.
For information about operating a CICS region with XRF, see the CICS Operations and Utilities Guide.
Table 26 shows how the effect of the START parameter depends on the state of the CICS global catalog and system log.
START
parm. |
State of global catalog | State of system log |
Result at restart |
---|---|---|---|
Any. | Not defined to VSAM. | Any. | JCL error. |
INITIAL | Defined. | Any. | CICS performs an initial start. The global catalog and system log 7 are initialized. |
COLD | Defined but contains no recovery manager control record. | Any. | After prompting for confirmation, CICS performs an initial start. The global catalog and system log 7 are initialized. |
COLD | Contains recovery manager records. | Not defined or dummy or empty. | Message DFHRM0401 is issued. Startup fails. |
COLD | Contains recovery manager records. | Contains records from previous run. | CICS performs a cold start. Recovery records in the system log that relate to changes to local resources are deleted. |
AUTO | Defined but contains no recovery manager control record and no AUTOINIT autostart override. | Any. | Message DFHRM0137 is issued. Startup fails. |
AUTO | Contains a recovery manager AUTOINIT autostart override. | Any. | CICS performs an initial start, without prompting. The global catalog and system log 7 are initialized. |
AUTO | Contains a recovery manager control record that does not indicate an initial start, and an AUTOCOLD autostart override. | Contains records from previous run. | CICS performs a cold start. Recovery records in the system log that relate to changes to local resources are deleted. |
AUTO | Contains recovery manager records, but no AUTOINIT override. | Not defined or dummy or empty. | Message DFHRM0401 is issued. Startup fails. |
AUTO | Contains a recovery manager control record indicating an initial start. | Any. | CICS performs an initial start. The global catalog and system log 7 are initialized. |
AUTO | Contains a recovery manager control record indicating a cold start, and no autostart override. | Contains records from previous run. | CICS performs a cold start. Recovery records in the system log that relate to changes to local resources are deleted. |
AUTO | Contains a recovery manager control record indicating an emergency start, and no autostart override. | Contains records from previous run. | CICS performs an emergency start. |
AUTO | Contains a recovery manager control record indicating a warm start, and no autostart override. | Contains records from previous run. | CICS performs a warm start. |
Table 27 shows the effect of different types of CICS startup on the CICS trace, monitoring, statistics, and dump domains.
Domain |
State of the
CICS catalogs |
Warm or emergency start | Initial or cold start |
---|---|---|---|
Trace | Not relevant. | Domain initializes according to the system initialization parameters. | Domain initializes according to the system initialization parameters. |
Monitoring | The global catalog is newly initialized. | Domain initializes according to the system initialization parameters. | Domain initializes according to the system initialization parameters. |
Monitoring | The global catalog contains status of monitoring at the previous CICS shutdown. | Domain uses monitoring status from the catalog, but modified by any system initialization override parameters. | Domain initializes according to the system initialization parameters. |
Statistics | The global catalog is newly initialized. | Domain initializes according to CICS-defined system default values. | Domain initializes according to CICS-defined system default values. |
Statistics | The global catalog contains status of statistics at CICS shutdown. | Domain uses statistics status from the catalog. | Domain initializes according to CICS-defined system default values. |
Dump | The global catalog is newly
initialized. |
Domain initializes the dump table according to CICS-defined system default values. Other dump attributes are set by system initialization parameters. | Domain initializes an empty dump table, and takes CICS-defined default action for all dump requests. Other dump attributes are set by system initialization parameters. |
Dump | The global catalog contains dump status at CICS shutdown. | Domain reads the dump table and dump status from the catalog. Other dump attributes are modified by any system initialization parameters. | Domain initializes an empty dump table, and takes CICS-defined default action for all dump requests. Other dump attributes are set by system initialization parameters. |
In a VTAM® network, the session between CICS and VTAM is started automatically if VTAM is started before CICS. If VTAM is not active when you start CICS, you receive the following messages:
F vtamname,USERVAR,ID=generic-applid,VALUE=specific-applid
+DFHSI1589D 'applid' VTAM is not currently active.
+DFHSI1572 'applid' Unable to OPEN VTAM ACB - RC=xxxxxxxx, ACB CODE=yy.
Although the MODIFY NET, USERVAR command is only significant when you are running CICS with XRF, the USERVAR message occurs for both XRF=YES and XRF=NO CICS systems. If you receive messages DFHSI1589D and DFHSI1572, and if the CICS region is not initializing as an alternate CICS region, you can start the CICS-VTAM session manually when VTAM is eventually started, by means of the CEMT SET VTAM OPEN command from a supported MVS™ console or a non-VTAM terminal.
If VTAM is active, but CICS still cannot open the VTAM ACB because VTAM does not recognize the CICS APPLID, you receive the following messages:
F vtamname,USERVAR,ID=generic-applid,VALUE=specific-applid
+DFHSI1592I 'applid' CICS applid not (yet) active to VTAM.
+DFHSI1572 'applid' Unable to OPEN VTAM ACB - RC=00000008, ACB CODE=5A.
This may be caused by an error in the value of APPLID operand, in which case you must correct the error and restart CICS. For information about other causes and actions, see the CICS Messages and Codes.
An XRF alternate CICS region cannot initialize properly until it has successfully opened the VTAM ACB.
Because VTAM and the alternate CICS region may be initialized concurrently, it is possible that several tries may have to be made to open the VTAM ACB. If VTAM is not active, the following message is written to the system console every 15 seconds:
DFHSI1589D 'applid' VTAM is not currently active.
If VTAM is active, but CICS cannot open the VTAM ACB, the following messages are written to the system console:
+DFHSI1572 'applid' Unable to OPEN VTAM ACB - RC=xxxxxxxx, ACB CODE=yy.
DFHSI1590 'applid' XRF alternate cannot proceed without VTAM.
CICS abends with a dump (abend code 1590).
In addition to loading the system initialization table at the start of initialization, and reading any other parameters from PARM, SYSIN, or the system console, the parameter manager domain is responsible for the management of the SIT. With the exception of the application domain (AP) which uses the SIT directly, the parameter manager domain passes system initialization parameters to the other CICS domains on request.
The domain initialization process is as follows:
For details of the parameters that are ignored when you specify NEWSIT=YES, see the NEWSIT parameter description in topic NEWSIT.
Whichever type of startup is performed, when the message:
DFHSI1517 - 'applid': Control is being given to CICS.
is displayed on the operating system console, CICS is ready to process terminal requests. (applid is the value of the specific APPLID system initialization parameter.)
When the startup process is completed, users are able to enter transactions from any terminals that are connected to CICS. For information about the CICS-supplied transactions, see CICS Supplied Transactions.