Changing the system definition online

You do not always need to rerun a complete IMS™ system definition to make changes to the IMS subsystem. Examine the changes to see if an online change can be made.

If the request does not involve changes to the IMS network or to static terminals, you can probably make the change online.

The procedure to make changes to the IMS online system can be summarized as:

  1. If necessary, make required system definition Stage 1 input changes.
  2. If necessary, perform a MODBLKS system definition.
  3. If necessary, run the MFS Language and MFS Service utilities.
  4. If necessary, generate DBDs, PSBs, and ACBs.
  5. As necessary, use the Online Change Copy utility to produce suitable copies of the IMS.MODBLKS, IMS.ACBLIB, and IMS.FORMAT, data sets.
  6. Issue the appropriate online change command sequence to make the online change at the proper time. The changes must be copied from the inactive library for a library switch OLC.
  7. Verify that the required changes took place.

If you need to undo or back out an online change, repeat the online change command sequence without changing the inactive libraries.

Parent topic: Overview of the local online change function