TD vs TS

Temporary Storage and Transient Data both move data through queues, but they solve different problems. Picking the wrong one is a classic CICS beginner mistake.

How they differ

• Access: TS reads randomly by item number or sequentially; TD reads sequentially only, with no item numbers.
• Reads: TS reads leave the record in place and it can be read again; TD reads are destructive and the record is gone.
• Updates: TS supports REWRITE of an existing item; TD has no update at all.
• Creation: TS queues are created automatically on the first WRITEQ; TD queues must be predefined with a TDQUEUE definition.
• Triggers: TD intrapartition queues can automatically start a transaction at a trigger level; TS has no triggers.
• Reach: TD extrapartition queues hand data to batch jobs, tapes and printers outside CICS; TS never leaves the region.
• Delete: TS deletes whole queues with DELETEQ TS; TD deletes intrapartition queues with DELETEQ TD.

When to use TD

• Data flows one way in order: logging, audit trails, report printing.
• You want CICS to start work automatically when enough data arrives - the ATI trigger pattern.
• The consumer is outside CICS: a batch program, a tape, or a printer.
• Each record is processed exactly once and then discarded.

When to use TS

• You need to find records again by number, or read them more than once.
• Short-lived scratch data: holding a record while the user edits it, paging through screens.
• You need REWRITE to update a stored record in place.
• Programs in the same region share data quickly without predefined definitions.

Example:-