Application Migration Considerations › Application Migration Considerations › Replacing Online Applications › Important Considerations

Important Considerations

The following considerations while disabling an active online application are:

• If the application to disable is running in multiple CICS regions or partitions, execute the DISABLE command in each region. This is true for each standalone CICS region and each AOR region in an MRO environment.
• When the DISABLE time arrives, the users running the specified application are not immediately purged. Their runs are aborted at the next transaction boundary (when the user presses a PF key or the Enter key or when a panel is transmitted) after the disable time arrives. For programs and panels in VLS format, the enqueues on those programs and panels are not released until the run is actually aborted. If a user left the terminal before the disable time arrives, those enqueues are not released until the user returns and presses the Enter key or a PF key.

  These enqueues prevent the transport utility from running or a new version of a program from being marked to PROD status since an exclusive enqueue on those programs and panels is requested from the operating system. In this case, eliminating these enqueues requires a DEQUEUE command be issued for each program and panel enqueued before running the object transport utility or issuing the MARK STATUS command. This is not a problem for application programs and panels in load module format since the runtime executor uses no enqueues in this case.

• It is not possible to disable a particular subprogram or portion of a
  run-unit. Specifying a subprogram name instead of the main program name is ineffective. The program name specified in the DISABLE command must be the same program name specified in the RUN command.
• If a new version of a program is replaced and multiple applications use it, each of those applications must be disabled.
• If a new version of a program is replaced without issuing a DISABLE command or in some way making sure that all users are off the application, different kinds of internal errors can occur. The most common error, “IDADOMLD07 - Global storage DT discrepancy for PGM pgm-name VER ver found” indicates that the updateable and reentrant portion of a program is not synchronized. If the updateable portion of a program is in CICS temporary storage while the reentrant portion of the program is replaced, this synchronization error is detected the next time the reentrant part of the program is loaded into memory.
• The DISABLE command stays in effect until it is explicitly released with the ENABLE command or until CICS is shut down and restarted.

The ENABLE RUN command allows users to start running applications that were previously disabled.

If DISABLE and ENABLE commands are executed after an end user left an active run of that application, the run still aborts when the user returns to continue the run. This is true even if the application was enabled before the session was continued. This is because the user was running a program that is replaced and the updateable portion of the program is from the old version of the program while the reentrant portion of the program is from the NEWCOPY copy. To synchronize all program components, the run must still be aborted and the user must restart the application.