>From my point of view, it would be enough to at least detect a stack
overflow, so that a Lisp error can be triggered, instead of having the
process die with a segfault.

I don't know how you'd do this on, say, a Linux system. But I can tell you from my own experience that it can be done on Windows, and that it involves some *serious* low-level hackery. Worse, the nature of those hacks is that they are intrusive, i.e. if they were implemented in the ECL DLL, they would change and maybe even break the behavior of the embedding app. Hence, I'd try to exhaust all other options first.