Troubleshooting Db2

This section discusses problem determination for CICS® Db2®.

These topics contain Diagnosis, Modification or Tuning information.

Thread TCBs (task control blocks)
In the CICS Db2 environment, each thread into Db2 runs under a thread task control block (TCB). This section provides further technical information about thread TCBs, to assist with problem determination.
Wait types for CICS Db2
The CICS Db2 task-related user exit, DFHD2EX1, issues WAIT_MVS calls for different purposes. These calls are distinguished by their resource name and type values. The resource name and resource type values are visible in the dispatcher section of a CICS system dump and also appear on the CEMT INQUIRE TASK panel as Hty and Hva values respectively.
Messages for CICS Db2
Messages issued by the CICS Db2 attachment facility use the DFHDB prefix which is also used for CICS DBCTL messages. Message numbers are in the range 2000 through 2999 and are reserved for CICS Db2. Thus CICS Db2 attachment messages are of the form DFHDB2xxx.
Trace for CICS Db2
The CICS Db2 attachment facility uses AP domain trace points in the range 3100 to 33FF.
Dump for CICS Db2
Control blocks from the CICS Db2 attachment facility are formatted out in a CICS system dump under the control of the Db2 keyword of the CICS IPCS verbexit.
Db2 thread identification
A thread executing in Db2 on behalf of a CICS transaction is identified by its correlation ID, which is set by the CICS Db2 Attachment Facility.
Transaction abend codes for CICS Db2
The CICS Db2 attachment facility uses multiple abend codes, each of which is unique to a particular error.
Execution Diagnostic Facility (EDF) for CICS Db2
The CICS Db2 task-related user exit, DFHD2EX1, is enabled with the FORMATEDF keyword and is called by CICS to format the screen for SQL API requests when the transaction is being run under EDF.
Handling deadlocks in the CICS Db2 environment
Deadlocks can occur in a CICS Db2 system between two or more transactions or between one transaction and another Db2 user. Deadlocks can involve one or two resources.

Parent topic: Troubleshooting and support