for having an stable system which limit option is good for ulimit comand ?
2-is any option for making asterisk crash-free?
it is possible, but not recommended. There is a reason, why the asterisk
process needs 100% of CPU.
What is your scenario?
How many extension?
What type of extensions? (SIP, etc)
How many concurrent calls?
You are trying to cure the symptom, not the cause 😉