Description

   The DCX$COMPRESS_DONE routine deletes the context area and
   sets the context variable to zero, undoing the work of the
   DCX$COMPRESS_INIT routine. Call DCX$COMPRESS_DONE when all data
   records have been compressed (using DCX$COMPRESS_DATA). After
   calling DCX$COMPRESS_DONE, call LIB$FREE_VM to free the virtual
   memory that DCX$MAKE_MAP used for the compression/expansion
   function.