

 DCBFID:       ______
   Calling sequence:                 ________________
   CALL DCBFID(u,b,n,ist)
     where:     u is integer unit number
                b is buffer where file
               name is returned
                n is buffer length in bytes
              ist is a status indicator
   Description           ___________:
   Returns in buffer b, left justified and blank
   padded to n bytes, the file name to which unit
   u is assigned. If u is assigned to a device the
   buffer will be blank.

   ist, the status indicator is set to the following
   value:
    Value     _____ Unit assigned to                ________________:
    0 null
    1 file
    2 CP-V labeled tape
    3 device
    4 ANS labeled tape

   If file name is longer than the buffer length, the name
   is truncated to n bytes.
