The Return Virtual Memory Statistics routine returns to its
    caller one of six statistics available from calls to LIB$GET_
    VM/LIB$FREE_VM and LIB$GET_VM_PAGE/LIB$FREE_VM_PAGE. Unlike
    LIB$SHOW_VM, which formats the values for output and displays
    them on SYS$OUTPUT, LIB$STAT_VM returns the statistic in the
    value-argument argument. Only one of the statistics is returned
    by each call to LIB$STAT_VM.

    Format

      LIB$STAT_VM  code ,value-argument

1  –  Returns

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by value

2  –  Arguments

 code

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

    Code specifying which statistic is to be returned. The code
    argument contains the address of a signed longword integer that
    is this code.

    Code  Statistic

    1     Number of successful calls to LIB$GET_VM
    2     Number of successful calls to LIB$FREE_VM
    3     Number of bytes allocated by LIB$GET_VM but not yet
          deallocated by LIB$FREE_VM
    5     Number of calls to LIB$GET_VM_PAGE
    6     Number of calls to LIB$FREE_VM_PAGE
    7     Number of VAX pages or Alpha pagelets allocated by LIB$GET_
          VM_PAGE but not yet deallocated by LIB$FREE_VM_PAGE

    Note that it is invalid to omit code or to give a code of 0 or 4.

 value-argument

    OpenVMS usage:user_arg
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference

    Value of the statistic returned by LIB$STAT_VM. The value-
    argument argument contains the address of an unsigned longword
    integer that is this value.