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.

The following points apply to all first phase PLTPI programs:

Second phase PLT programs

During the final stages of CICS initialization, most CICS services are available to PLT programs. These programs are specified in the second part of the PLTPI list (after the DFHDELIM entry). The limitations on the services that are available to second phase PLTPI programs are described below.

Effect of delayed recovery on PLTPI processing

Because recovery processing does not take place until PLTPI processing is complete, PLT programs may fail during an emergency restart if they attempt to access resources protected by retained locks. If PLT programs are not written to handle the LOCKED exception condition, they abend with an AEX8 abend code.

If successful completion of PLTPI processing is essential before your CICS applications are allowed to start, consider alternative methods of completing necessary PLT processing. You may have to allow emergency restart recovery processing to finish, and then complete the failed PLTPI processing when the locks have been released.

Related tasks
Writing shutdown programs
Related reference
General considerations when writing initialization and shutdown programs
[[ Contents Previous Page | Next Page Index ]]