$ENQW

   Queues a lock on a resource. The $ENQW service completes
   synchronously; that is, it returns to the caller when the
   lock has been either granted or converted. For asynchronous
   completion, use the Enqueue Lock Request ($ENQ) service; $ENQ
   returns to the caller after queuing the lock request, without
   waiting for the lock to be either granted or converted. In
   all other respects, $ENQW is identical to $ENQ. See the $ENQ
   description for all other information about the $ENQW service.

   The $ENQ, $ENQW, $DEQ, and $GETLKI services together provide the
   user interface to the Lock Management facility.

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

   Format

     SYS$ENQW  [efn] ,lkmode ,lksb ,[flags] ,[resnam] ,[parid]

               ,[astadr] ,[astprm] ,[blkast] ,[acmode] ,[rsdm_id]

   C Prototype

     int sys$enqw  (unsigned int efn, unsigned int lkmode,

                   struct _lksb *lksb, unsigned int flags,

                   void *resnam, unsigned int parid, void

                   (*astadr)(__unknown_params), unsigned __int64

                   astprm, void (*blkast)(__unknown_params),

                   unsigned int acmode, unsigned int rsdm_id,...);