Zend Server for IBM i 8.5 includes a new version of the ibm_db2 extension, version 1.9.7. ibm_db2 1.9.7 changes the defaults for a couple of important directives and introduces some new ones. This article tells where these changes are documented and provides a copy of the notes for convenient reference.
Zend Server for IBM i version 8.5 or higher, running on any supported version of IBM i.
At the time of this writing, the documentation for ibm_db2 at php.net has not yet been updated with the new directives for version 1.9.7. This update will occur soon.
Here is text copied from that page that describes the final changes that may impact the way ibm_db2 works with your application:
The default changes can provide better performance, and align more correctly with the default behavior of the DB2-CLI interface. However, if problems occur, please consider changing the directives to use the older default behaviors, as noted in the first section, above.