If there isn't an open_cursors in your init.ora, then the system will take a default value which is too low for many applications. Just add the line to your init.ora and restart the database instance.
By the way... You might want to go to 255 open cursors instead of just 100. The difference in memory utilization is relatively small.
-- Michael
Darkstreak Computing & Innovations
www.darkstreak.com