Transaction failure program

The abnormal condition program has been divided into two programs, DFHTFP and DFHACP, according to function. During transaction abend processing, DFHTFP is invoked after transaction initialization on abnormal termination. Its purpose is to reset the status of a terminal attached to the transaction, and to send a message informing the terminal operator that the transaction has abended. DFHTFP also calls the user-written (or default) program error program (DFHPEP), and writes a message to the CSMT transient data destination. DFHTFP resolves any abnormal conditions other than those associated with a terminal, or those handled directly by the operating system. DFHACP is invoked by transaction manager whenever an incorrect transaction is detected.

Design overview

Errors can be classified as belonging in either of two broad categories:

DFHTFP

Task abnormal conditions, which are detected by CICS® control programs and are often due to an application program destroying system control information. When this happens, the task is terminated, the program error program (DFHPEP) is called, the terminal operator is, if possible, informed of the error, and the error is logged at destination CSMT. If the transaction has entered syncpoint processing, then DFHPEP is NOT called.

DFHACP

Operator errors, such as incorrect transaction identifiers, security key violations, or failure of an operator to sign on to the system before attempting to communicate with CICS. When any of these happens, the program error program is NOT called, the terminal operator is notified, and the error is logged at destination CSMT.

Figure 1 and Figure 2 show the interfaces between the abnormal condition programs, DFHTFP and DFHACP, and other components when an error has been detected.

Note:

1. DFHTFP is invoked by transaction manager whenever a task is abnormally terminated. The operator ID for error messages is in the terminal control table terminal entry (TCTTE) at TCTTEOI. DFHTFP returns to transaction manager after the error message has been issued. When a task is abnormally terminated because of a stall purge condition, the stall purge count is increased by one and the transaction identifier (from the installed resource definition) is included in the error message.
2. DFHTFP communicates with storage control to obtain and release terminal input/output areas (TIOAs).
3. DFHTFP links to the user-supplied (or default) program error program by issuing a DFHPGLU LINK_URM domain call, which passes a parameter list via a COMMAREA (mapped in this case by DFHPCOM TYPE=DSECT). Any abend within a DFHPEP program results in control returning to DFHTFP unless there is an active HANDLE ABEND for this program. See Program error program for further information about the DFHPEP program.
4. DFHTFP and DFHACP both write error messages to the transient data destination, CSMT, by calling the message domain.

Note:

1. DFHACP is invoked by transaction manager whenever an incorrect transaction code is detected.
2. DFHTFP and DFHACP both write error messages to the transient data destination, CSMT, by calling the message domain.