First quiesce stage

During the first quiesce stage of shutdown, all terminals are active, all CICS® facilities are available, and a number of activities are performed concurrently.

The following activities are performed:
  • CICS invokes the shutdown assist transaction specified on the SDTRAN system initialization parameter or on the shutdown command.

    Because all user tasks and JVM servers must terminate during the first quiesce stage, it is possible that shutdown could be unacceptably delayed by long-running tasks (such as conversational transactions). The purpose of the shutdown assist transaction is to allow as many tasks as possible to commit or back out cleanly, while ensuring that shutdown completes within a reasonable time.

    CICS obtains the name of the shutdown assist transaction as follows:
    1. If SDTRAN(tranid) is specified on the PERFORM SHUTDOWN command, or as a system initialization parameter, CICS invokes that tranid.
    2. If NOSDTRAN is specified on the PERFORM SHUTDOWN command, or as a system initialization parameter, CICS does not start a shutdown transaction. Without a shutdown assist transaction, all tasks that are already running are allowed to complete.
    3. If the SDTRAN (or NOSDTRAN) options are omitted from the PERFORM SHUTDOWN command, and omitted from the system initialization parameters, CICS invokes the default shutdown assist transaction, CESD, which runs the CICS-supplied program DFHCESD.

    The SDTRAN option specified on the PERFORM SHUT command overrides any SDTRAN option specified as a system initialization parameter.

  • The DFHCESD program started by the CICS-supplied transaction, CESD, escalates through PURGE to KILL. By doing this, long-running tasks and JVM servers are shut down (see The shutdown assist transaction).
  • Tasks that are automatically initiated are run—if they start before the second quiesce stage.

    If external resource managers such as Db2®, IBM® MQ and TCPIP are shut down before the tasks start running, the tasks will fail with an AEY9 abend. To avoid AEY9 abends, follow the advice in Avoiding AEY9 abends.

  • Any programs listed in the first part of the shutdown program list table (PLT) are run sequentially. (The shutdown PLT suffix is specified in the PLTSD system initialization parameter, which can be overridden by the PLT option of the CEMT or EXEC CICS PERFORM SHUTDOWN command.)
  • A new task started as a result of terminal input is allowed to start only if its transaction code is listed in the current transaction list table (XLT) or has been defined as SHUTDOWN(ENABLED) in the transaction resource definition. The XLT list of transactions restricts the tasks that can be started by terminals and allows the system to shut down in a controlled manner. The current XLT is the one specified by the XLT=xx system initialization parameter, which can be overridden by the XLT option of the CEMT or EXEC CICS PERFORM SHUTDOWN command.

    Certain CICS-supplied transactions are, however, allowed to start whether their code is listed in the XLT or not. These transactions are CEMT, CESF, CLR1, CLR2, CLQ2, CLS1, CLS2, CSAC, CSTE, and CSNE.

  • Finally, at the end of this stage and before the second stage of shutdown, CICS unbinds all the z/OS® Communications Server SNA LUs and devices.

The first quiesce stage is complete when the last of the programs listed in the first part of the shutdown PLT has executed, all user tasks are complete and all JVM servers are shut down. If the CICS-supplied shutdown transaction CESD is used, this stage does not wait indefinitely for all user tasks to complete.