(Alpha and I64 only.) The Return Virtual Memory Statistics
    routine returns to its caller one of six statistics available
    from calls to LIB$GET_VM_64 and LIB$FREE_VM_64, as well as
    LIB$GET_VM_PAGE_64 and LIB$FREE_VM_PAGE_64. Unlike LIB$SHOW_
    VM_64, which formats the values for output and displays them on
    SYS$OUTPUT, LIB$STAT_VM_64 returns the statistic in the value-
    argument argument. Only one of the statistics is returned by each
    call to LIB$STAT_VM_64.

    Format

      LIB$STAT_VM_64  code ,value-argument