IMS is not operational

Problem
IMS(TM) is not operational.
Symptoms
More than one symptom is possible:
System action
WebSphere MQ detects the IMS error and:
System programmer action
None.
Operator action
Resolve and correct the problem that caused IMS to terminate abnormally, then carry out an emergency restart of IMS. The emergency restart: You might need to restart the connection to WebSphere MQ with the IMS command:
/START SUBSYS subsysname

During startup, IMS requests the adapter to resolve in-doubt units of recovery.