[gpderetta]

Technically you could manually grow coroutine stacks the same way the kernel does for thread stacks, by mapping on fault and periodically unmapping everything beyond the red zone. But the complexity would be significant and hard to make it efficient without kernel support.

[saurik]

For a while there was an exciting patch for gcc called split stacks that provided a little thunk for every function -- one normally bypassed, but which stackless coroutines could opt in to call -- that would check if more stack had to be allocated, but I think the story was that Go was the primary potential customer for it and they decided to just give up on the dream :(.

[gpderetta]

You can use segmented stacks in c++ just fine I think. I believe boost.coroutine supports it. The problem is the additional overhead and the impossibility to link against any non-split stack code.