--- COMMIT MODE PDF hierarchy!

Currently, changes to the --- COMMIT MODE pdf are only recognized when a transaction completes.

This means that if you are in COMMIT MODE=END and you change to COMMIT MODE=PCF CYCLE, the change won't be recognized until your process ends (or until you execute a COMMIT or ROLLBACK statement).

Also, we need to establish a hierarchy (similar to the hierarchy that we use for DEFAULT MODE) that determines the precedence for the COMMIT PDF when you invoke a child process.