Depends on the implementation. Support for TCO means that an unbounded amount of tail calls can be active at a time. A normal call pushes a frame to the stack.

Depends on the implementation. Support for TCO means that an unbounded amount of tail calls can be active at a time. A normal call pushes a frame to the stack. Most implementations don't push a frame for a tail call. However when debugging is turned on, one could keep, say, the 10 last frames corresponding to tail calls. That would give you the best of both worlds.