Multitasking

The CICS adapter optimizes the performance of a CICS to WebSphere MQ connection by exploiting multi-processors and by removing work from the main CICS task control block (TCB), allowing multiple MQI calls to be handled concurrently.

The adapter enables some MQI calls to be executed under subtasks, rather than under the main CICS TCB that runs the application code. All the CICS adapter administration code, including connection and disconnection from WebSphere MQ, runs under the main CICS TCB.

The adapter attaches eight z/OS subtasks (TCBs) to be used by this CICS system. We cannot modify this number. Each subtask makes a connect call to WebSphere MQ. Each CICS system connected takes up nine of the connections specified on the CTHREAD system parameter. This means that increase the value specified for CTHREAD by nine for each CICS system connected. MQI calls can flow over those connections. When the main connection is terminated, the subtasks are disconnected and terminated automatically.