Cannot access memory at address xxx, stack overflow management ?

I reduce my code footprint to 181kbyte program size / 1866kbyte stack+heap but I still have problems.

I had several time these messages :

"Previous frame inner to this frame (corrupt stack?)"

and/or:

"Cannot access memory at address @xxx", addresses are very close to the stackpointer.

"Execution is suspended because of error.

Watchdog has expired. Target detached."

...

Before trying to use a bigger memory (4Mbyte instead of 2) or deeply modify my code (no recursive call inside), I would like to have more informations about these errors. Sometimes they occurs after 1s and sometimes after 5mn with the same use. In debug mode with runtime_stack_checking enabled, I don't manage to identify the source of my problems (IDE messages are not each time the same).

Thanks for answers.