OCI8のDRCPサポートはPHP5.3/OCI8 1.3.0から

タイトルが全てですが。。。ｗ

I've merged connection pooling (DRCP) and Fast Application Notification (FAN) suport to PHP 5.3's OCI8 extension. The PHP 5.3 OCI8 code is Beta - in fact, PHP 5.3 itself is still really "Development". (It would be handy to have problems reported before PHP 5.3 goes Production).

PHP5.1/5.2で使いたい場合、現状だとPHP5.3のsnapshotから取り出して使う事になるようです。