Regarding high memory threads in FSM

Hi Experts,

This is regarding high memory usage in FSM. In  FSM  12 there are two application parameters called

•  ABORT_HIGH_MEMORY_THREADS
• ABORT_HIGH_MEMORY_THRESHOLD

My questions are

1. Is there any recommended limit of Memory threshold to abort threads in bytes?
2.  How to measure long processing query to abort?
3. How much time need to consider as a long processing query?
4. Is there anything that we can control the time?

Thanks,
Oshan