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Chapter 3. Shutdown and restart recovery
CICS can shut down normally or abnormally and this affects the way that CICS
restarts after it shuts down.
CICS can stop executing as a result of:
v A normal (warm) shutdown initiated by a CEMT, or EXEC CICS, PERFORM
SHUT command
v An immediate shutdown initiated by a CEMT, or EXEC CICS, PERFORM SHUT
IMMEDIATE command
v An abnormal shutdown caused by a CICS system module encountering an
irrecoverable error
v An abnormal shutdown initiated by a request from the operating system
(arising, for example, from a program check or system abend)
v A machine check or power failure
Normal shutdown processing
Normal shutdown is initiated by issuing a CEMT PERFORM SHUTDOWN
command, or by an application program issuing an EXEC CICS PERFORM
SHUTDOWN command. It takes place in three quiesce stages, as follows:
First quiesce stage
During the first quiesce stage of shutdown, all terminals are active, all CICS
facilities are available, and the a number of activities are performed concurrently
The following activities are performed:
v CICS invokes the shutdown assist transaction specified on the SDTRAN system
initialization parameter or on the shutdown command.
Because all user tasks 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.
© Copyright IBM Corp. 1982, 2010 25