Transient data queues - IBM Mainframe

The CICS transient data control facility provides a generalized queuing facility. Data can be queued (stored) for subsequent internal or external processing. Selected data, specified in the application program, can be routed to or from predefined symbolic transient data queues: either intrapartition or extrapartition.

Transient data queues are intrapartition if they are associated with a facility allocated to the CICS region, and extrapartition if the data is directed to a destination that is external to the CICS region. Transient data queues must be defined and installed before first reference by an application program. You can:

  • Write data to a transient data queue (WRITEQ TD command)
  • Read data from a transient data queue (READQ TD command)
  • Delete an intrapartition transient data queue (DELETEQ TD command)

An intrapartition TDQ is a group of sequential records, which are produced and processed within a CICS region. All Intrapartition TDQs are stored in only one physical file in a CICS region. The application program can access the records sequentially and the record will be logically removed from the queue, or in other words the READ of a TDQ is destructive.

An extrapartition TDQ is a group of records written sequentially which interfaces between the transactions of the CICS region and the systems outside the CICS region. Each Extrapartition TDQ is a separate physical file, which means that each file must be open within the CICS region when it is used by the CICS transaction. While DCT entries determine the initial OPEN/CLOSE status of a file, but it can be opened or closed through CEMT during a CICS session. The following sections describe the commands related to TDQs.

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