Introducing changed applications in an active IMS system

When introducing a changed application program into an active IMS system, the UPDATE PGM START(REFRESH) command is useful for some region types.

By using the UPDATE PGM START(REFRESH) command, you can roll out the application program change easily without having to find out all of the regions that the program is scheduled in and stopping the regions manually.

The UPDATE PGM START(REFRESH) command is supported for programs scheduled in the following region types:
  • MPP pseudo-wait-for-input (PWFI) regions in which the program is scheduled and the program is not preloaded by the DFSMPLxx PROCLIB member
  • JMP PWFI regions in which the specified program name is scheduled
  • MPP, JMP, and message-driven BMP regions in which the program is scheduled and that are running a transaction defined as WFI=YES
The UPDATE PGM START(REFRESH) command is not supported for the following region types:
  • MPP regions where the program is loaded by the DFSMPLxx PROCLIB member
  • IFP regions
  • JBP regions
  • Non-message-driven BMP regions

To ensure that a refreshed copy of a changed application program is loaded into these region types, follow these steps:

Procedure

  1. Issue the /DISPLAY PGM command to identify associated transactions that are using the application program that you are changing.
  2. Issue the /DISPLAY TRAN command to identify the scheduling class for each transaction identified in step 1.
  3. Issue the /DISPLAY ACT command to identify the dependent regions that are capable of processing the scheduling classes identified in step 2.
  4. Stop the application program that you are changing by issuing the /STOP PGM command.
  5. Refresh the program.
  6. Stop and restart all dependent regions identified in step 3. Stopping and restarting these regions one at a time allows the remaining active regions to process transactions that are not associated with the stopped program during this process.
  7. Start the changed application program.