@brson and I talked about this, and we're still pretty uncomfortable without overflow checks on 32-bit. By *default* tasks have 2MB stacks, but if you're looking for scalability on 32-bit you're going to obviously spawn with smaller tasks than that. 64K is a pretty reasonable stack size, so there's some clear danger that we're going to hit this limit.

I see two ways out of this:

1. Implement overflow checking for 32-bit only (and fail)
2. Investigate all our target platforms, make sure that there is a 64-bit CAS operation for all of them, and then implement that.