Sending form XCOM for z/OS to XCOM for Windows.
The xcom.glb and xcom.log from Windows did not contain any additional clues as to what went wrong.
Release : 11.6
XCOM for Windows
XCOM for z/OS 12.0
Cause cannot be determined in this case without an XCOM trace from the Windows side
Restarting the xcomd service resolved the problem.
If the problem recurs, get a trace from the Windows side which is where the problem is happening and send in with the xcom.glb and xcomlog from both sides.