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Chapter 4. Writing initialization and shutdown programs
You can write programs to run during the initialization and shutdown phases of
CICS processing. Any program that is to run at these times must be defined to
CICS in a program list table (PLT). Information about how to code the PLT is
provided in the CICS Resource Definition Guide.
This information is divided into the following sections:
1. “Writing initialization programs”
2. “Writing shutdown programs” on page 428
3. “General considerations when writing initialization and shutdown programs” on
page 429.
Writing initialization programs
Any program that is to execute during CICS initialization must be specified in a
program list table (PLT), and the suffix of that PLT must be named on the program
list table post initialization (PLTPI) system initialization parameter.
There are two phases of program list table (PLT) execution, separated by the
DFHDELIM statement in the PLT.
First-phase PLT programs
During the early stages of CICS initialization processing, the only PLT programs that
can execute are those containing the enabling commands for global and
task-related user exit programs. These programs are specified in the first part of the
PLTPI list (before the DFHDELIM statement). This allows you to enable those exit
programs that are needed during recovery.
Dynamic LIBRARY resources will be installed, or restored and re-activated, after
first stage PLT programs run, but before second stage PLT programs run. This
means that first stage PLT programs must be included in data sets in DFHRPL, but
second stage PLT programs can be included in, and loaded from dynamic LIBRARY
resources.
The following points apply to all first-phase PLTPI programs:
v The programs must be written in assembler language.
v They must run AMODE 31.
v The only EXEC CICS commands they should contain are:
– ASSIGN APPLID
– ASSIGN INITPARM
– ENABLE
– EXTRACT EXIT
Because this stage occurs before recovery when initialization is incomplete, no
other CICS services can be invoked.
v If a first-phase PLTPI program enables an exit program that issues any of the
XPI calls INQUIRE_MONITORING_DATA, MONITOR, TRANSACTION_DUMP, or
WRITE_JOURNAL_DATA, it must not specify the START option on the EXEC
CICS ENABLE COMMAND.
© Copyright IBM Corp. 1977, 2011 425