Default transaction isolation level.

Hi,

I think my first post got lost, so here we go again:

I'm running a J2EE server (JBoss 3.0.4) with postgresql 7.0.3. I have
been experincing a promlem with "memory leaks", where the postgresql
jdbc driver calls addWarning with the message NOTICE: TRANSACTION
ISOLATION LEVEL is READ COMITTED and those SQLWarning objects never get
freed. The addWarring operation seemes to get called for every call the
J2EE server makes to postgresql.

So I thoght that if I changed the default isolation level in postresql
to serilazible that warning might dissapere, but I can't find any docs,
faq:s or mails stating how I can do that.

So I think my question is:

How do I change the default isolation level on the postgresql backend.

/Tommy