public function close()
    {
        // call QGYCLST, the "close list" api.
        $apiPgm = 'QGYCLST';
        $apiLib = 'QSYS';

        $requestHandle = $this->_requestHandle;

        $paramXml = "<parm io='in' comment='1. request handle'>
                      <data var='requestHandle' comment='Request handle: binary/hex' type='4b'>$requestHandle</data>
                    </parm>\n" . Toolkit::getErrorDataStructXml(2); // param number 2

        // pass param xml directly in.
        $this->ToolkitSrvObj->PgmCall($apiPgm, $apiLib, $paramXml);

        // GUI0006 means end of list
        if ($this->ToolkitSrvObj->getErrorCode()) {
            return false;
        } else {
            return true;
        }
    }