Starting up CICS

When you start up CICS®, you start a process called CICS system initialization. This process must finish before you run any transactions.

CICS system initialization involves many activities, some of which are:

If you are operating CICS with CICS recovery options, backout procedures may be used to restore recoverable resources to a logically consistent state. Backout occurs if you start CICS in one of the following ways:

For background information about backout, and recovery and restart, see the CICS Recovery and Restart Guide.

The types of CICS startup

CICS startup can be any of the following types:

Startup type
Effect
Initial
CICS starts with no reference to any system activity recorded in the CICS global catalog and system log from a previous run of CICS. For more information, see CICS actions on an initial start.
Cold
CICS starts with limited reference to any system activity recorded in the CICS global catalog and system log from a previous run of CICS. For more information, see CICS actions on a cold start.
Warm
CICS starts, after a normal shutdown, restoring CICS to the status it was in at the last normal CICS shutdown, except for some facilities that it initializes as for a cold start. CICS always restores the trace domain according to the system initialization parameters, and can restore other facilities depending on the COLD option of their associated system initialization parameters. For more information, see CICS actions on a warm start.
Emergency
CICS starts, after an abnormal shutdown, restoring recoverable resources to their committed states. For more information, see CICS actions on an emergency restart.

When CICS is started, the type of startup (and therefore the actions it takes) depends primarily on the following:

The values of other system initialization parameters also influence the actions taken on CICS startup.

For information about the types of startup, the roles of the CICS catalogs, and the effect of the START system initialization parameter, see the CICS System Definition Guide.

Note:
You cannot explicitly request a warm or emergency restart. When selecting the type of start (using the START system initialization parameter), the choices are INITIAL, COLD, or AUTO. AUTO can result in a warm or an emergency restart; CICS itself determines which to use.

CICS actions on an initial start

The CICS global catalog and system log are initialized, and all information in them is lost. Because resynchronization information for remote systems is not preserved, damage may be done to distributed units of work.

It should rarely be necessary to perform an initial start. Examples of times when an initial start is necessary are:

CICS actions on a cold start

In a cold start, initialization of CICS occurs with limited reference to any system activity recorded in the CICS catalogs. With the exception of resynchronization information for remote systems noted below, no system log or warm keypoint information is used from any previous run of CICS. Dump table entries from a previous run are also deleted in a cold start.

In a cold start:

CICS actions on a warm start

A warm start restores certain elements of the CICS components that can be warm started to the status that was recorded in the warm keypoint of the previous normal shutdown.

A partial warm start is similar to a complete warm start, except that some selected CICS facilities are cold-started, as specified in the system initialization parameters. Information is obtained for those facilities from the warm keypoint only if they are not specified to be cold started.

In a warm start:

CICS actions on an emergency restart

A CICS system that operates on resources, such as files, that have been defined by the installation to be recoverable, records changes to those resources in the CICS system log. If the CICS system fails, the system log at the time of failure should typically contain records of changes made by tasks that have not completed (‘in-flight’ tasks) and by others that have completed.

Following an abnormal termination, Recovery Manager collects all of the log records pertaining to in-flight tasks. It acquires locks on any records that they updated and restores the tasks as shunted UOWs, to be backed out after initialization is complete.

CICS-VTAM actions after an emergency restart

When LU-LU sessions are re-established after an emergency restart (and subsequent processing), CICS participates in a resynchronization protocol with logical units to discover if any messages, in either direction, were lost when CICS was terminated.

The logical units for which resynchronization is required will have been marked in the TCTTEs. Resynchronization is not attempted in the following cases:

Note:
If the previous session abended, the use of COLDACQ overrides CICS integrity control. This could lead to data integrity problems. Also, you should check the CSMT log for an activity keypoint after the restart of a session following a CICS failure. If there is no activity keypoint, you should issue COLDACQ again after the next emergency restart.

For each logical unit that does require resynchronization, CICS issues an STSN command that notifies the logical unit of the sequence numbers known to CICS--that is, those numbers that backout processing placed in the TCTTE. The logical unit can compare these sequence numbers with those that it has logged for itself, and can thus determine if any messages were lost.

Note:
The message remains in the resend slot if CICS does not retransmit it. This occurs if the resynchronization process shows that the output message was not lost, or if the logical unit does not support the STSN command; the 3270 is in this category.

CICS startup and the VTAM session

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 manual.

Concurrent initialization of VTAM and XRF alternate CICS regions

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).

End of CICS startup

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.

Related concepts
Controlling CICS operation
Shutting down CICS
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