After a long struggle i finally found something that works!
PDO::oci does not support REF CURSORS. Reference: php.net/manual/en/ref.pdo-oci.php
But for Yii there is a workaround by using oci8 which supports cursors and is well supported by Yii.
Yii has oci8 extensions. Which makes using oci8 easier and its better in terms of performance compared to pdo_oci.
Happy Coding Guys!