Recursive (or any kind of) SQL statements have nothing to do with maximum number of sessions exceded! Oracle is not complaining about maximum naumber of cursors opened, it is complaining because there is too many sessions on your system!

The reason could be that either
- you have physical limit of max sessions in your init.ora too low
or
- something (firewall or something like that) is terminating the connections to the database in a "ungracefull"v maner and PMON is not able to clean those terminated sessions from the RDBMS
or
- something else ....????

You should check regulary after your database has been up for some time if the number of database sessions is constantly increasing. If yes, you should check if there is many sessions with status KILLED that will not go away even after quite a long time since their last activity.

Do you have MTS configuration?