Specifying THREADWAIT for the CICS DB2 attachment facility

The THREADWAIT parameter of DB2CONN and DB2ENTRY defines whether the requests for a thread should be queued, abended, or sent to the pool thread in the case of a shortage of entry or command threads. If THREADWAIT=YES is specified instead of THREADWAIT=POOL the transaction is queued rather than sent to the pool thread.

Effects

Using THREADWAIT=YES avoids the thread initialization and termination overhead. If a transaction is made to wait because of the lack of entry threads, a queueing arrangement is necessary. This is done by the CICS® DB2® attachment facility. The advantages of this are that, once the entry thread finishes its current piece of work, it continues with the next transaction immediately.

Where useful

In a high-volume, highly-utilized system using DB2.

How implemented

THREADWAIT is defined in the DB2CONN and DB2ENTRY definitions of the CICS DB2 attachment facility.

How monitored

The following facilities are available to monitor the CICS DB2 attachment facility.

Related tasks
Database management for performance
Tuning the CICS DB2 attachment facility: Introduction
Setting TCBLIMIT, THREADLIMIT, CTHREAD and MAXOPENTCBS for the CICS DB2 attachment facility
Specifying PRIORITY for the CICS DB2 attachment facilitySelecting authorization IDs for performance and maintenance
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