Overriding CICS-generated TERMIDs

If you are using CICS-generated TERMIDs and have specified a different prefix, reserved for virtual terminals, on each region on which Client terminals can be installed, there should be no clash of names, either in the regions in which the virtual terminals are installed, or when different regions ship Client definitions to the same AOR.

However, if you are using CICS-generated TERMIDs, your server programs must not rely on TERMIDs being allocated consistently to particular Client terminals.

A Client terminal can be deleted by a Client sending a CICS®_EpiDelTerminal request, by a user shutting down a Client terminal emulator or the Client itself, or if a connection failure occurs. When it is reinstalled, CICS does not necessarily generate the same TERMID as it had previously. This could create problems if, for example:

Your server programs derive temporary storage queue names from the TERMID (to associate each queue with a particular user). Problems of data mismatch could occur if the queue is not deleted by transaction end (possibly due to a failure).
The best solution is for your application programs always to check before creating a temporary storage queue whether a queue of the same name already exists, and, if so, to delete it. However, if you have a large number of server applications, it may not be possible to check or change them all.
Your server programs record TERMIDs for later use. For example, an application might issue an EXEC CICS START TERMID command, with a time interval after which the transaction is to be initiated against the named terminal. If, during the delay interval, the virtual terminal is deleted, and re-installed with a different TERMID, the started transaction could fail because the TERMID no longer exists.

If your server programs cannot be rewritten, it may be necessary for your autoinstall control program to create aliases for the CICS-generated TERMIDs. It could, for example, use a mapping file to relate particular aliases to particular Client workstations (identified by connection name).

If your server programs are located on a back-end AOR, the autoinstall control program is invoked in the AOR when a virtual terminal is shipped in, just as for any other shipped definition. It can, if necessary, allocate an alias terminal identifier to the shipped definition. (For details of writing a control program to install shipped definitions, see Writing a program to control autoinstall of shipped terminals.)