is it worth to create coroutine inside coroutine?

[ReiiSky]

i just wondering what's technique to create co inside co, does its affect performance.

by example i want to create few co inside non-main co, so what should i do, like:

1. creating share stack variable in global heap instead in co local variable?
2. how much stack size for main share stack and share stack inside co-main function?

also one more question, documentation said to allocate local variable (especially the big one) on the heap, then what usage stack in a function good for? there is some technique to calculate how much w should allocate the share stack size?

i need advise for this, i hope someone give me some tips or anything.

thanks, sorry for my bad english.