I've got it... In ext_tables: $myPid = intval(unserialize($GLOBALS['TYPO3_CONF_VARS']['EXT']['extConf']['my_ext'])['myPid']); \TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPageTSConfig(' [PIDinRootline = ' . $myPid . '] ... [] '); Kind regards, Jan