Limit switches on a lathe

I'm looking at where to place the limit switches on my cnc lathe conversion. The cross slide is obvious, but I'm not sure what to do on the long axis (z?) given that the position of the switches will be dictated by what chuck I have installed, and the position of the tail stock.

How is this normally done? I'm using servos, so I want some protection against run away.

Thanks,
Frank