Hi there Mrutyunjay,
As for the number of open cursors exceeding the value you specified: I do hope you realize that the number of open cursors speciefied in the init.ora file is a per-session value. As your text is not exactly clear whether the number you give are for the instance as a whole or only for your session, the easiest explanation seems to be that those numbers are instance-wide.
Good riding,
Rudy.