Dequeues (unlocks) granted locks; dequeues the sublocks of a
    lock; or cancels an ungranted lock request. The calling process
    must have previously acquired the lock or queued the lock request
    by calling the Enqueue Lock Request ($ENQ) service.

    On Alpha and Integrity server systems, this service accepts 64-
    bit addresses.

    Format

      SYS$DEQ  [lkid] ,[valblk] ,[acmode] ,[flags]

    C Prototype

      int sys$deq  (unsigned int lkid, void *valblk, unsigned int

                   acmode, unsigned int flags);