processes get full on Oracle XE... how to change?

Hello,
I'm using Oracle 10g XE on my windowsXP machine. I have a java 1.5 JDBC client that thru a connection pool opens and closes connections.
If I request connections from the pool and release them, and I do this fast and many times, Oracle will answer me with a ORA-12519, TNS:no appropriate service handler found

I see that processes are full:

select * from v$resource_limit where resource_name in ('processes','sessions');

RESOURCE_NAME CURRENT_UTILIZATION MAX_UTILIZATION INITIAL_ALLOCATION LIMIT_VALUE
processes 20 40 40 40
sessions 24 43 49 49

The problem may be resolved by increasing the Oracle processes parameter maybe ?
If so, how can I do that ?
I'm novice on Oracle, I tried to add the parameter "processes=150" and "sessions=150" in the files:
C:\Sviluppo\Oracle\app\oracle\product\10.2.0\server\dbs\init.ora C:\Sviluppo\Oracle\app\oracle\product\10.2.0\server\config\scripts\init.ora but that didnt work.
I actually do not know where to change what.

Could you please give me some hint, or point to some documentation (I coundt find anything enough clear and resolutive)

thank you very much for any help Received on Fri Sep 01 2006 - 11:10:10 CDT