Jboss 6.4 - JPA 2.0 Oracle stored procedure

Question

Before I start to explain my issue, I would like to add that I have gone through all question already asked related to my subject but did not found a suitable answer as a solution.

I have a Webservice SOAP based. It is running in JBoss application version 6.4

The only compatible version of JPA is 2.0 but not beyond.

Case: I need to call a stored procedure written in Oracle This procedure feds a table inside Then, I just want to do a select from that table How to do that ?

I have tried to use createNativeQuery

createNativeQuery("{ call procedure() }"); 

but this crashes the Webservice request with the error : JAVA.LANG.NEGATIVEARRAYSIZEEXCEPTION

Could you please advice as per your most related experience where JBoss cannot be upgraded. I know it is non sense but it is that way.

Thank you