Activating user exits for data tables

To activate the data table user exits, you need to perform the following steps:

  1. Decide which user exits you want to use. A description of each user exit is included in Customizing data tables using user exits.
  2. Write the user exit programs. Examples are included in Appendix. Sample user exit programs.
  3. Define the user exit programs to CICS®, using the CEDA DEFINE PROGRAM command as described in the CICS Resource Definition Guide.
  4. Activate the user exits, using the EXEC CICS ENABLE command as described in the CICS System Programming Reference. If required, you can later deactivate the user exits using the EXEC CICS DISABLE command.

Unless you control the opening of a data table explicitly, with a CEMT or EXEC CICS command, you should probably activate the user exits during CICS startup. Otherwise the loading of the data table might begin before the user exits are activated. To activate the user exits during startup, you need to:

  1. Write one or more program list table postinitialization (PLTPI) programs that include the EXEC CICS ENABLE commands to activate the user exits (for programming information about PLTPI programs, see the CICS Customization Guide).
  2. Define a program list table (PLT) with an entry for each of those PLTPI programs, as described in the CICS Resource Definition Guide.
  3. Specify the PLTPI=suffix parameter for system initialization, as described in the CICS System Definition Guide. Use the suffix of the PLT that was defined in the previous step. This causes the PLTPI programs to be executed in the second stage of initialization, before any files are opened.

You can use PLT shutdown (PLTSD) programs in a similar way to disable the user exits during CICS shutdown.

Related concepts
Operations with data tables
Opening a data table
Closing a data table
MVS JCL requirements when using shared data tables
Interpreting data table statistics
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