The Oracle JDBC driver (classes12.zip) is a 1.9MB embarrassment. You could try the Seropto driver from i-net software... it's only 92k, doesn't rely on proprietary extns to JDBC, and is the only type4 Oracle 8 driver than is sun certified... (and certainly handles large CLOBs for us quite nicely).
I have been trying to get the Seropto driver working for several days.
If I use the org.inet.ora.XDataSource class, I get some XAER_NOTA errors. If I use this configuration with the Tyrex transaction manager, things seem to work (for a while), but the server eventually hangs.
If I use the wrapper XA class provided by JBoss, things _SEEM_ to work (for a while), but the server eventually hangs.
Since you're using the Seropto driver, can you tell me:
1- What transaction manager do you use?
2- Which DataSourceClass do you use?
3- Did you need to do anything funky with the Xid class?
Can you attach your jboss.jcml and (if you're using Tyrex), you're domain.xml?