Every recursion can be converted to code that uses only a single stack. Tail calls can be easily eliminated at compile time automatically as well, that’s why it

Every recursion can be converted to code that uses only a single stack. Tail calls can be easily eliminated at compile time automatically as well, that’s why it only needs compile-time support — I don’t specifically know what Scala/etc do, but the mentioned trampoline is basically just a function pointer one can jump to, accumulating results in some non-stack data structure if needed.