Datacom CICS Services not reconnecting after a MUF abend

Products

• Datacom

Issue/Introduction

After a Datacom Multi-User facility  (MUF) abend and restart, Datacom CICS Service Facility is not reconnecting automatically to the MUF.

Environment

z/OS

DATACOM CICS SERVICES 15.1

 

Cause

After a MUF abend, Datacom CICS Service facility has the capability to reconnect to the MUF automatically as long as the application work load keeps coming in and the failed MUF gets restarted and fully activated.

There is no need for manual intervention if all the steps in the automatic reconnect process complete successfully.

If the MUF and the application CICS regions are up and running and connected together and actively processing requests, when the MUF fails at some point, an application request from CICS to MUF will receive a Datacom Return Code of 86. 

This return code will trigger the following process in the CICS Service facility :

1. The CICS Service facility will issue the command disconnect immediate (RSET IMMEDIATE=01 ) from the failing MUF in order to release all the threads and all the resources including the storage required to communicate with the now failed MUF.
2. As the application work load comes into the CICS region to requesting a CA Datacom/DB service, the CICS Service Facility will keep trying to re-establish the connection back to the failed MUF. 
3. The first few attempts will fail while waiting for the MUF to be restarted and activated, but once the MUF is activated, the next attempt to connect would be successful and the request would be honored and the system back to normal processing.

Any abends during this process can prevent the auto-reconnect process from being completed successfully. 

Resolution

If the CICS Service Facility is not reconnecting within a couple of minutes of the MUF restarting and activating, do the following:

1. issue the command DBOC SHUTDOWN 
2. issue the command DBOC STARTUP 
   

This will allow any other non-DATACOM application work to proceed uninterrupted and would act just like a CICS recycle for the Datacom related applications.

Alternatively, perform a recycle of the CICS region.

Additional Information

See documentation section Recovery and Restart Procedures.