On DB2 v7.2 for Windows , when NOT FENCED UDFs execute concurrently I get the following error

[IBM][CLI Driver][DB2/NT] SQL4304N Java stored procedure or user-defined
specific name "SQL021218111144613" could not load Java class "rtUDFs",
reason code "1". SQLSTATE=42724

This does not happen when one UDF executes at the time.
Also,when the UDFs are registered as fenced this behavior is not observed.

Surprisingly, on DB2 v8 NOT FENCED UDFs execute concurrently without giving any problems.
In DB2 v8, UDFs are registered as thread safe by default and share a single JVM.Is there any way to ensure that in v7.2 a single JVM is loaded at a time for concurrently executing UDFs.
Is there any other workaround or fix for this error?Will tuning any of the
memory parameters help?
I found a similar message posted by Jan Posthuma in dbforums archive.

Is there any solution to this problem on 7.2? Applying The latest fixpack8 also does not solve this.

- Vijay