Intrapartition destinations(TDQ) can be predefined with a trigger level and triggered transaction. When the number of entries in the destination reaches that level, the triggered transaction is automatically initiated (started).
Typically, the triggered transaction processes the records that are on the queue. The transaction uses a principal facility to determine how it runs, as follows:
File: The transaction runs as a background task on the same CICS region as that on which the queue is running.
Terminal: The transaction writes to a local or remote terminal.
System: The transaction takes part in a Distributed Transaction Processing (DTP) conversation with a back-end transaction on another CICS region.
After the queue has been emptied, a new ATI cycle begins. That is, a new task is scheduled for initiation when the specified trigger level is again reached, whether or not execution of the earlier task has ended.