For some reason, I shutdown the database and it freeze up 500 M of memory which is 1/4 of the entire database server. I understand that each user logged in the system will allocate certain memory them but when they logged off the system I thought those allocated memory will be released. Is there any set up I have to config in the init.ora for it automatically to release the memory whn the user logged off.

Please give me some detail and solutions of how to handle it.

Thanks