Another workaround for DB2 v9.7 and UDB type 4 driver is to add property file named DB2JccConfiguration.properties somewhere to the application CLASSPATH with following content:
db2.jcc.override.progressiveStreaming=2
db2.jcc.override.fullyMaterializeLobData=true
First line forces DB2 UDB driver to turn off "progressive streaming" feature. Second one instructs the driver to load all LOB data during FETCH (this is ignored unless progressive streaming is turned off).
Clues leading to this workaround:
http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/index.jsp?topic=/com.ibm.db2.luw.apdv.java.doc/doc/c0052411.html
https://jira.jboss.org/browse/JBPAPP-2613
More about UDB type 4 properties: http://publib.boulder.ibm.com/infocenter/db2luw/v9/index.jsp?topic=/com.ibm.db2.udb.apdv.java.doc/doc/rjvdsprp.htm.
Anyways, those 2 lines saved my day.