When trying to issue DCMT VARY AREA OFFLINE or RETRIEVAL, it is sometimes possible that the command will abend with a 3018 abend code.
The most common cause of this is that the underlying FILE is not locked by the CV.
When an area is in update mode to an IDMS CV, there is a locking bit set in the first file within the area. It is possible that through a procedural error in maintenance, the CV will be in a situation where an area is in update mode to the CV, but the locking bit is not set on.
If you attempt to issue DCMT VARY AREA OFFLINE or RETRIEVAL against such an area, you will get a 3018 abend code.
In order to fix this, issue the command DCMT VARY FILE xxx ACTIVE against the first file in the area. This will reset the locking bit without altering the area's status within the CV.
After that, an attempt to vary an area to OFFLINE or RETRIEVAL should be successful.