On Alpha and Integrity server systems, deletes a virtual region
    within the process's address space, including all created virtual
    addresses within the region.

    This service accepts 64-bit addresses.

    Format

      SYS$DELETE_REGION_64  region_id_64 ,acmode ,return_va_64

                            ,return_length_64

    C Prototype

      nt sys$delete_region_64  (struct _generic_64 *region_id_64,

                               unsigned int acmode, void

                               *(*(return_va_64)), unsigned __int64

                               *return_length_64);

1  –  Arguments

 region_id_64

    OpenVMS usage:region identifier
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by 32- or 64-bit reference
    The region ID associated with the region to be deleted. The
    region ID specified must be one returned by the $CREATE_REGION_64
    service. You cannot specify VA$C_P0, VA$C_P1, or VA$C_P2.

 acmode

    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode associated with the call to $DELETE_REGION_64. The
    acmode argument is a longword containing the access mode.

    The $PSLDEF macro in STARLET.MLB and the file PSLDEF.H in
    SYS$STARLET_C.TLB define the following symbols and their values
    for the four access modes:

    Value      Symbolic Name      Access Mode

    0          PSL$C_KERNEL       Kernel
    1          PSL$C_EXEC         Executive
    2          PSL$C_SUPER        Supervisor
    3          PSL$C_USER         User

    The most privileged access mode used is the access mode of the
    caller. The caller can delete pages only if those pages are owned
    by an access mode equal to or less privileged than the access
    mode of the caller.

    Once all pages are deleted within the region, the region can be
    deleted only if the region is owned by an access mode equal to or
    less privileged than the access mode of the caller.

 return_va_64

    OpenVMS usage:address
    type:         quadword address
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The lowest process virtual address of the pages that
    $DELETE_REGION_64 has successfully deleted. The return_va_64
    argument is the 32- or 64-bit virtual address of a naturally
    aligned quadword into which the service returns the virtual
    address of the first page deleted. Virtual addresses are deleted
    from low address to high address, regardless of the direction in
    which virtual addresses expand for that region.

 return_length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The length of the virtual address range that $DELETE_REGION_64
    has successfully deleted. The return_length_64 argument is the
    32- or 64-bit virtual address of a naturally aligned quadword
    into which the service returns the length of the deleted virtual
    address range in bytes.