Yes, but I don't think that's more true of TailCallHelper than of any function calls using a stack. This sounds like it's saying that even with tail call optim

Yes, but I don't think that's more true of TailCallHelper than of any function calls using a stack. This sounds like it's saying that even with tail call optimization it's possible for the arguments to a function to be too big for the stack. For example, if the arguments you pass to the recursive function call are stack allocated and grow each time then each call will increase stack usage, even though it's reusing the space from the previous call.