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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
.
The chapter is divided into the following sections:
1. “Initialization programs”
2. “Shutdown programs” on page 394
3. “General considerations” on page 396.
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.
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 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.
v First phase PLTPI programs must not enable any task-related user exit program
with the TASKSTART option.
v You do not have to define first phase PLTPI programs to CICS. If you do not,
default definitions are installed automatically by CICS. Note that this happens
whether or not program autoinstall is specified as active on the PGAIPGM
© Copyright IBM Corp. 1977, 1999 393