SIC LOCK

        [SIC\]SIC LOCK [LockFile]

    With no argument, display the list of lock files owned  by  the  current
    program  session.  With  a  file name as argument, create this file as a
    lock file. Attempting to create a lock file which already  exists  is  a
    fatal  error.  Lock  files  owned by the current program session are im-
    plicitely deleted when exiting.

    This command is intended to protect some user's resources, e.g. invoking
    it  in  a  procedure ensures that this procedure can not be run twice in
    the same or in another session.