This C/370 program is a controller in a context where there is a need to regulate the MQ activity generated by the LegStar MQ handler LSMQHBIN.
When a request queue is defined with trigger type FIRST, message handlers such as LSMQHBIN are single threaded which might result in long response times when activity increases. If the trigger type is EVERY, there is a risk for the CICS region to be flooded since each MQ message immediately generates a CICS transaction.
LSMQCBIN assumes a trigger type of FIRST but will actually start several LSMQHBIN handlers if the request queue depth justifies so.
The program limits the number of simultaneous handlers though in order to prevent flooding. The limit is set at the handler TRANCLASS level.