Cancel a MUF task with no sequence number or number changing too quickly

Products

• Datacom
• DATACOM - AD
• Datacom/AD
• Datacom/DB

Issue/Introduction

The REQABORT command requires a request sequence number to abort a request.

A COMM STATUS shows the task does not have a number in the SEQ column or the sequence number changes very quickly.

How can this task be cancelled?

 

Environment

Release: All releases

Cause

You can only use REQABORT if a task has a SEQ number displayed in the COMM STATUS.

The format of the command in DBUTLTY is:

COMM OPTION=REQABORT,REQSEQNO=nnnnnnnn 

Or from the console issue: 

F mufjob,REQABORT nnnnnnnn

The SEQ is an internal request sequence number and is only displayed while the task has a request active.
Sometimes the SEQ is blank which means there is no active request or changes very quickly if many requests are being processed quickly.
In these cases REQABORT cannot be used.

Resolution

You can instead use the Transaction Sequence Number (TSN) with the TSN_ABORT command.
A TSN is assigned to a task when an update command is issued  so if no update command has been issued the task will not have a TSN either and TSN_ABORT cannot be used.

The format of the command in DBUTLTY is:

COMM OPTION=CONSOLE,OPTION2='TSN_ABORT nnnnnnnn' 

Or from the console issue: 

F mufjob,TSN_ABORT nnnnnnnn

Another way to cancel a task is with the TASK_ABORT command using the task number but this will only work with single task connections to the MUF which are inactive, for example a task from TSO or a batch JOB. This will not work for tasks from CICS or Server which can have multiple connections to the MUF.

The format of the command in DBUTLTY is: 

COMM OPTION=CONSOLE,OPTION2='TASK_ABORT n' 

Or from the console issue: 

F mufjob,TASK_ABORT n

Additional Information

See the Datacom 15.1 documentation section TSN_ABORT and  TASK_ABORT. 

If the problem is in CICS that has been COLD started (this can be seen from a MUF STATUS command), a warm start should take care of the tasks that were in-doubt. You now need to run MUF STATUS and decide if you need to use REQROLBK sequence number for that ROLBK task or REQCOMIT