signal stack

[Subra Maniam]

Can somebody list out the possible situations where the usage of a separate
stack for a signal handler is helpful? 

I can think of two possible situations where it may be useful.

1) some kind of thread management within a process.
2) some debugger routine which is part of the same process.

But my ideas are vague and in any case I am not sure if there is a situation
where the absence of this facility will be really felt? I will be thankful
if someone can throw some light.

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