Making local online changes in a sysplex

IMS does not automatically coordinate local online changes across a sysplex. Use global online change to coordinate online change across a sysplex. This topic describes how to manually coordinate local online changes across a sysplex.

Recommendation: Clone your IMS subsystems and share libraries (ACBLIB, MODBLKS, FORMAT) across the sysplex. MODSTAT IDs must be the same across the sysplex.

To prepare for performing IMS online change in a sysplex environment:

Procedure

  1. Use an Automated operator (AO) application program. The AO application program should be able to:
    • Stop resources you want to change or delete.
    • Handle online change exception conditions for an individual IMS subsystem.
    • Issue the /MODIFY PREPARE or /MODIFY ABORT commands.

    Design the AO exit routine to look for the online change messages that IMS issues and to take the suggested action. Design an AO application program or use an automation tool to issue commands to resolve any online change problems.

  2. Define the active, inactive, and staging libraries.
  3. Share the active and inactive libraries.

    All IMS subsystems that you want to be able to change online should also share the staging libraries.

  4. Define each IMS (with its own MODSTAT data set).

    Each IMS must have its own MODSTAT data set, with the same active and inactive ACBLIB, FMTLIB, and MODBLKS definitions.

  5. Start each IMS.

To perform the online changes:

  1. Perform system definitions on the staging libraries for changes.
  2. Run the Online Change Copy utility.
  3. Issue the /MODIFY PREPARE command for each IMS subsystem.

    You can have either the IMS operator or an AO application program issue this command. If the command fails on any IMS subsystem in the sysplex, the operator or AO application program must issue the /MODIFY ABORT command on all IMS subsystems for which the /MODIFY PREPARE succeeded.

  4. Optional: Stop all resources that will be changed or deleted.

    This step greatly increases the chance that the online change will succeed for an individual IMS subsystem.

  5. Resolve any work in progress.
  6. Issue the /DISPLAY MODIFY command.

    Use the /DISPLAY MODIFY command to display the work in progress for resources to be changed or deleted, before attempting the COMMIT phase. When COMMIT is successful, the modifications persist across all IMS restarts, unless global online change occurs while an IMS is down.

  7. Issue /MODIFY ABORT|COMMIT for each IMS subsystem.
  8. Start resources that were changed or added.