The Free Virtual Memory from Program Region routine deallocates
    an entire block of contiguous bytes that was allocated by a
    previous call to LIB$GET_VM. The arguments passed are the same
    as for LIB$GET_VM.

    Format

      LIB$FREE_VM  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:longword_signed
    type:         longword integer (signed)
    access:       read only
    mechanism:    by reference

    Number of contiguous bytes to be deallocated by LIB$FREE_VM.
    The number-of-bytes argument is the address of a signed longword
    integer that contains this number. The value of number-of-bytes
    must be greater than zero.

    Byte counts are rounded in the same manner as in LIB$GET_VM.

                                   NOTE

       You may omit the number-of-bytes argument if you are using
       boundary tags (LIB$M_VM_BOUNDARY_TAGS).

 base-address

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

    Address of the first byte to be deallocated by LIB$FREE_VM.
    The base-address argument contains the address of an unsigned
    longword that is this address. The value of base-address must be
    the address of a block of memory that was allocated by a previous
    call to LIB$GET_VM.

 zone-id

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

    The address of a longword that contains a zone identifier created
    by a previous call to LIB$CREATE_VM_ZONE or LIB$CREATE_USER_VM_
    ZONE.

    You must specify the same zone-id value as when you called
    LIB$GET_VM to allocate the block. An error status will be
    returned if you specify an incorrect zone-id. The zone-id
    argument is optional. If zone-id is omitted or if the longword
    contains the value 0, the 32-bit default zone is used.