It is possible that the server was unable to cancel all sessions because a session was encountered that could not be cancelled. Some sessions may still remain active after the command completes.
Server operation completes.
Specify a session_number with the CANCEL SESSION command to cancel a specific CLIENT session. If a SERVER session is active, the partner server must be quiesced for the session to end. The SERVER session may be active with a Storage Agent, Library Client, Library Server or Virtual Volume server. To prevent new sessions from starting, see the DISABLE SESSIONS command.