$EXECUTE PROCEDURE fails in ONLINE 6.0 TP/XA

Anyone running ONLINE 6.0 in a TUXEDO 4.2.2 system as an XA-compliant resource manager? If yes, here is our problem: We've got a simple Tuxedo service (in SQL/C of course) that executes a stored procedure to insert a row in a table and obtain the primary key's serial value. The first time the service is called, everything is fine. But, any subsequent time, error -267: The cursor has been previously released and is unavailable' is returned. Now, the XA standard 'says' that db resources are released at the end of the service. So what's the right way to call a stored procedured from within an XA-compliant server? Cheers, Leo