I can't see any way of doing this directly, without using an additional param.
But logically, within your proc, can you assume that the nesting level can either:
1) Remain the same
2) Decrement by one to a minimum of zero
3) Increment by one
?
If yes, maybe you can handle it by restricting the magnitude of the jumps in the nesting level using brute-force coding.
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.