TS Queues

A TS queue is the basic unit of temporary storage. Everything you store is stored in a named queue, and every queue is made of numbered items.

The queue name

• Every TS queue is identified by a unique queue name, also called the data-id.
• With the QUEUE option the name can be 1 to 8 characters; with QNAME it can be up to 16 characters.
• Names must be unique across the CICS region, so programs commonly build the name with the terminal id from EIBTRMID, for example 'TRM1MNT3'.
• A queue name is like the label on a folder: it tells CICS exactly which set of records you mean.

Items and item numbers

• Each record written to a TS queue is called an item, and CICS assigns it the next sequential item number, starting at 1.
• The item number is not stored inside the record; it is only the address you use to find the record again.
• You can read items randomly by giving the item number, or sequentially with the NEXT option.
• If you write 4 records, they become items 1, 2, 3 and 4, in the order they were written.

Creating a queue

• You do not define a TS queue before using it. The first WRITEQ TS with a new name creates the queue automatically.
• Queues live in main storage or in the DFHTEMP file on disk, decided by the MAIN or AUXILIARY option on WRITEQ TS.
• A queue stays in storage until you delete it with DELETEQ TS, so always clean up queues you no longer need.

Sharing queues between tasks

• Any task in the CICS region can read or write any TS queue by name, which makes queues handy for passing data between programs.
• Sequential position is shared: any task can move the NEXT pointer, so two tasks reading the same queue sequentially can interfere.
• If two tasks must not touch the same queue at the same time, use the EXEC CICS ENQ command to reserve it exclusively.

Example:-