phpGrid DB2 Starter or the phpGrid Full version?
The phpGrid v7 can support "native" DB2 driver, which probably has better performance. Hence, it is preferable.
If you also need to use the DB2 connection options (See http://php.net/manual/en/function.db2-connect.php) such as i5_naming, i5_lib, etc, it will need one simple update in the database class 'cls_db.php' to include one additional parameter array that is DB2 specific.
The update is now available to paid customers. Please contact support to acquire the update.