Fast Path Transaction Retry

Fast Path Transaction Retry (FPTR) is designed for IMS Fast Path users who cannot run the Fast Path trace permanently on their system because of its impact on performance, but want to have the trace turned on when Fast Path failures occur.

Fast Path problems can be resolved much faster when trace information is available to show the logic flow of a call or transaction.

FPTR is activated only when certain Fast Path failures occur. FPTR automatically allocates a trace data set, turns on the trace, and retries the transaction. If no abend occurs on the retry, FPTR issues a message, turns off the trace, and the system continues processing. If an abend does occur on the retry of the transaction, Fast Path trace writes the trace data, FPTR turns off the trace, and the system continues with Fast Path trace inactive. FPTR is not invoked for abends in BMP regions.

When you report certain IMS Fast Path problems to the IBM® Support Center, you will be asked if the Transaction Retry function failed. The following topics will help you determine what information to report.

Processing flow

A summary of the processing flow of FPTR follows:

  • The ESTAE exit of the dependent region controller receives control for abends U1026 and U1027, and all system abends except 122 and 222.
  • The ESTAE exit provides debugging information including:
    • Name of abending module
    • Last applied APAR of the abending module
    • Date and time of assembly of module

    If the failing module cannot be identified, a message informs the operator.

  • The ESTAE exit decides if the transaction can be retried. If so, the ESTAE requeues the failing input message for retry and produces a dump of the first abend.
  • Message DFS554A is sent to the master terminal.
  • The retry process starts in an eligible dependent region.
    • FPTR dynamically allocates a trace data set and starts Fast Path trace.
    • FPTR writes message DFS0785A to the master terminal and the JES2 job log.
  • When the retry of the transaction is complete, FPTR deallocates the trace data set and spools the contents of the trace data set to the SYSOUT class specified in the MSGCLASS parameter on the JOB statement of the dependent region.

System programmer tasks

The system programmer should:

  • Print the job log.
  • Print the spooled trace data set information.
  • Save and analyze the above information.
  • Contact IBM Software Support for assistance, if needed.