Rules and considerations when using CICS queues

1. In CICS, both IMPORT and EXPORT require that you specify the QUEUETYPE option. There is no default.
2. When importing an object from a transient data (TD) queue in CICS, you must specify the correct object type; the queue is emptied once QMF retrieves its contents. For example, if you specify "Form" when the object type in the transient data queue is a procedure, QMF issues an error message. However, you cannot successfully issue the IMPORT command again (even with the corrected object type) using the same queue, because that queue is now empty.
3. In CICS, the transient data or temporary storage (TS) queue must contain a single, completed QMF object before you issue the IMPORT command.
4. If you export to a transient data queue, the queue must be open, enabled and empty before you issue the EXPORT command. For information about CICS transient data queues, see CICS for VSE/ESA Application Programming Guide

Considerations:

QMF handles CICS transient data queues differently than temporary storage queues.

• Transient data queues: QMF imports the entire transient data queue prior to displaying the object on the screen. This means that the contents of the entire queue must fit into your storage or spill area. It also means that, if the object to be displayed is large, there may be a delay before QMF displays the object on the screen.

  A CICS intrapartition transient data queue can hold up to 32K rows of data; an extrapartition transient data queue can be as large as it needs to be to hold the object.

• Temporary storage queues: QMF reads approximately 100 rows of temporary storage before displaying them to the user. A temporary storage queue can hold up to 32K rows of data.
• Adding a QMF object to the queue: QMF uses the SUSPEND parameter on the IMPORT and EXPORT commands to let CICS regulate when the command is run.

  The SUSPEND parameter on the IMPORT and EXPORT commands determines the action to be taken if a queue is busy. When the SUSPEND parameter is set to YES, QMF issues a CICS ENQ (enqueue) for the CICS data queue name. This tells CICS to wait until the queue is available before writing the QMF object to the queue, thus ensuring that the QMF transaction does not interfere with any other jobs being handled by the queue.

  When the SUSPEND parameter is set to NO, the EXPORT command is canceled and a message is returned. The default value of SUSPEND is NO. That QMF issues an automatic ENQ is reflected in the SUSPEND option of the EXPORT and IMPORT commands.