The MAXTHRD parameter specifies the maximum number of threads that this CICS® system may use up to a value of 255, or the limit imposed by MAXREGN. The default is 1 or the number defined by MINTHRD, whichever is the highest.
This parameter controls the maximum number of tasks for which this CICS system can have PSBs scheduled in DBCTL. Any requests to schedule a PSB when the MAXTHRD limit is reached is queued by the DRA.
MAXTHRD can be used in DBCTL systems to ensure that, at peak loads, additional threads can be built in addition to those already allocated as a result of MINTHRD, thus avoiding waiting for threads.
After the MINTHRD limit is exceeded, threads continue to be built up to the MAXTHRD limit but, because each thread’s control blocks are allocated during PSB scheduling, the pathlength is greater for the tasks running after the MINTHRD limit has been reached.
The MINTHRD and MAXTHRD parameters are specified in the DRA startup table (DFSPZP).
DBCTL statistics are available when the CICS/DBCTL interface is shut down normally. The MAXTHRD value is recorded (see DBCTL session termination statistics for further information). You can also use CICS auxiliary trace to check for queueing for threads and PSBs.