Resolution: It is configured in the Workflow file. For example workflow file "wfin26prodnotifretailer.xml" in the $MQ_COMMONDIR/…/workflow will have 60:0:0:0 as the value for the “expirydate” in the “NewWorkItem” activity. Which means that the workitem will timeout after 60 days?
After changing the value for timeout in the workflow file, it is not required to restart the server and also only the new workitems will have the new timeout setting applied.
To get more information on the workitem time out, please refer to workflow guide under the workitem activity.