On Alpha and Integrity server systems, deletes a range of virtual
    addresses from a process's virtual address space. Upon successful
    completion of the service, the deleted pages are inaccessible,
    and references to them cause access violations.

    This service accepts 64-bit addresses.

    Format

      SYS$DELTVA_64  region_id_64 ,start_va_64 ,length_64 ,acmode

                     ,return_va_64 ,return_length_64

    C Prototype

      int sys$deltva_64  (struct _generic_64 *region_id_64,

                         void *start_va_64, unsigned __int64

                         length_64, unsigned int acmode, void

                         *(*(return_va_64)), unsigned __int64

                         *return_length_64);