The internal Zend Studio debugger does not support i5/OS functions. The way to use Studio for i5/OS with your i5 is to use Remote Debugging.
PHP scripts return the wrong time of day, unless the time zone is set correctly. This article explains how to set up time zones for PHP on IBM i.
To safely remove Zend Core from your system after Zend Server for IBM i has been installed, please verify that you are at version 2.6.1 of Zend Core for IBM i5/OS. If you are at an earlier version, please upgrade to 2.6.1 before uninstalling Zend Core for IBM i5/OS. Uninstalling an earlier release of Zend Core for IBM i5/OS will cause ZENDADMIN and other user profiles to be deleted, along with any objects owned by these user profiles. This includes the objects in the Zend Server for IBM i library ZENDSVR.