Using the Oracle JDBC driver to persist JMS messages, I get the following exception when the message size reaches a given limit:

     java.sql.SQLException: Io exception: Software caused connection abort: socket write error
     at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
     at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:179)
     at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:334)
     at oracle.jdbc.ttc7.TTC7Protocol.handleIOException(TTC7Protocol.java:3678)
     at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1999)
     at oracle.jdbc.ttc7.TTC7Protocol.executeFetch(TTC7Protocol.java:1005)
     at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2158)
     at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2035)
     at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2876)
     at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:609)
     at org.jboss.resource.adapter.jdbc.CachedPreparedStatement.executeUpdate(CachedPreparedStatement.java:95)
     at org.jboss.resource.adapter.jdbc.WrappedPreparedStatement.executeUpdate(WrappedPreparedStatement.java:251)
     at org.jboss.mq.pm.jdbc2.PersistenceManager.add(PersistenceManager.java:980)

You should upgrade your driver to the latest 10g release

http://www.oracle.com/technology/software/tech/java/sqlj_jdbc/index.html