zone-id

    OpenVMS usage:identifier
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference

    Zone identifier. The zone-id argument is the address of an
    unsigned longword containing this identifier. Use zero to
    indicate the 32-bit default zone.

 detail-level

    OpenVMS usage:longword_signed
    type:         longword (signed)
    access:       read only
    mechanism:    by reference

    An identifier code specifying the level of detail required
    by the user. The detail-level argument is the address of a
    signed longword containing this code. The default is minimal
    information. The following are valid values for detail-level:

    0    zone-id and name
    1    zone-id, name, algorithm, flags, and size information
    2    zone-id, name, algorithm, flags, size information, cache
         information, and area summary
    3    zone-id, name, algorithm, flags, size information, cache
         information, area summary, and queue validation

 user-action-procedure

    OpenVMS usage:procedure
    type:         procedure value
    access:       function call (before return)
    mechanism:    by value

    Optional user-supplied action routine called by LIB$SHOW_VM_ZONE.
    By default, LIB$SHOW_VM_ZONE prints statistics to SYS$OUTPUT
    by means of LIB$PUT_OUTPUT. An action routine is useful when
    you want to return statistics to a file or, in general, to any
    location other than SYS$OUTPUT. If user-action-procedure fails,
    LIB$SHOW_VM_ZONE terminates and returns a failure code. Success
    codes are ignored.

 user-arg

    OpenVMS usage:user_arg
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value

    Optional 32-bit value to be passed directly to the action routine
    without interpretation. That is, the contents of the argument
    list entry user-arg are copied to the argument list entry for
    user-action-procedure.