* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
-class BaseStacker extends BaseFrameworkSystem {
+abstract class BaseStacker extends BaseFrameworkSystem {
// Exception codes
const EXCEPTION_STACKER_ALREADY_INITIALIZED = 0x050;
const EXCEPTION_STACKER_IS_FULL = 0x051;