PLT: program list table

A program list table (PLT) specifies programs that you want to run during CICS® startup and shutdown, and groups of programs that you want to enable and disable together.

You may want to generate several PLTs for one or more of the following reasons:
  • To specify a list of programs that you want to be executed in the second and third initialization stages of CICS startup. For more detail about the initialization stages, see Using post-initialization (PLTPI) programs. For programming information about restrictions on using programs in the initialization stages, see Writing initialization programs. The selected list should be specified at initialization time by the PLTPI=xx system initialization parameter, where xx is the suffix of the PLT that contains the required list of programs.

    For convenience, the list of programs selected for execution during initialization is referred to as the 'PLTPI' list.

  • To specify a list of programs that you want to be executed during the first and second quiesce stages of controlled shutdown. The selected list should be specified at initialization time by the PLTSD=xx system initialization parameter, where xx is the suffix of the PLT that contains the required list of programs.

    The PLT specified in the PLTSD system initialization parameter can be overridden at shutdown time by the PLT option in the CEMT PERFORM SHUTDOWN command.

    The shutdown PLT is normally loaded as CICS is being shutdown. However, it is possible to use the same PLT for both initialization and shutdown, and under these circumstances the PLT is loaded during initialization and CICS does not need to reload it during shutdown. If this is the case and the PLT is updated while CICS is operational, a CEMT SET PROGRAM NEWCOPY command must be issued for the PLT to ensure that the updated version is used when CICS is shutdown.

    For convenience, the list of programs selected for execution during shutdown is referred to as the 'PLTSD' list.

  • To specify a list of programs that you want to have enabled or disabled as a group by a main terminal ENABLE or DISABLE command. This use of PLTs means that a main terminal operator can enable or disable a set of programs with just one command, instead of using a separate command for each program.
Any number of PLTs can be generated for the purposes described here, provided that:
  1. Each PLT has a unique suffix
  2. Each program named in a PLT either has a program resource definition entry in the CSD file, or is capable of being autoinstalled (that is, the appropriate system initialization parameters have been specified for program autoinstall).
    Note: PLTs should not be defined as programs in the CSD.

First-phase PLT programs must be placed in the DFHRPL concatenated data sets, but second-phase PLT programs can be placed in a dynamic LIBRARY concatenation. However, CICS scans the LPA for phase 1 PLTPI programs if they are not already installed.

The following macros are available to define the PLT entries:
  • Control section: DFHPLT TYPE=INITIAL
  • Entries in program list table: DFHPLT TYPE=ENTRY
  • End of Program List Table: DFHPLT TYPE=FINAL (see TYPE=FINAL (end of table))