(Alpha and I64 only.) The Allocate Virtual Memory routine
    allocates a specified number of contiguous bytes in the program
    region and returns the 64-bit virtual address of the first byte
    allocated.

    Format

      LIB$GET_VM_64  number-of-bytes, base-address [,zone-id]

1  –  Returns

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

2  –  Arguments

 number-of-bytes

    OpenVMS usage:quadword_signed
    type:         quadword integer (signed)
    access:       read only
    mechanism:    by reference

    Number of contiguous bytes that LIB$GET_VM_64 allocates. The
    number-of-bytes argument is the address of a quadword integer
    containing the number of bytes. LIB$GET_VM_64 allocates enough
    memory to satisfy the request. Your program should not reference
    an address before the first byte address allocated (base-address)
    or beyond the last byte allocated (base-address + number-of-bytes
    minus 1) since that space may be assigned to another routine. The
    value of number-of-bytes must be greater than zero.

 base-address

    OpenVMS usage:address
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by reference

    First virtual address of the contiguous block of bytes allocated
    by LIB$GET_VM_64. The base-address argument is the address of an
    unsigned quadword containing this base address.

 zone-id

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

    The zone-id argument is the address of a quadword that contains a
    zone identifier created by a previous call to LIB$CREATE_VM_ZONE_
    64 or LIB$CREATE_USER_VM_ZONE_64. This argument is optional. If
    zone-id is omitted or if the quadword contains the value 0, the
    64-bit default zone is used.