The following restrictions apply to CICS® on System/390® server programs that are invoked from the Client External Presentation Interface (EPI):
A Client terminal can be deleted by the Client sending a CICS_EpiDelTerminal request, by an end 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 has implications for the way in which your server programs are written. For example:
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.
If your server programs cannot be rewritten, your autoinstall user program could allocate aliases to 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 user program is invoked in the AOR when a virtual terminal is shipped in, just as for any other shipped definition. It could, if necessary, allocate an alias terminal identifier to the shipped definition.
For information about writing an autoinstall user program to control the installation of Client virtual terminals and shipped definitions, see your CICS on System/390 Customization Guide.
Note also that an EPI client application
cannot:
A CICS on System/390 application can communicate with a Client-attached printer by starting a transaction against it, using an EXEC CICS START TERMID command.
A Client-attached printer accepts a 3270 data stream which contains set buffer address (SBA) commands, and a 3270 write control character (WCC) with the print bit set on. An application can use any of the following command sequences, followed by EXEC CICS PRINT, to print data successfully:
There are some restrictions: