One answer is:
A figure that I have seen many times for set mining is 1/12th of the smallest stack, if you think you can get your opponents stack. I think it was in Professional No Limit Hold'em Vol 1 also.
You are 150bb deep w/pocket 77's
villian 100bb deap w/AA (How you know this is irrelevant)
If the villian raises more than 8bb (100/12=8.34) you will not be getting the odds you need to set mine for his stack.
1/12th is used becuase you will not always get his stack if you hit your set and your set could still lose. You can also search set mining and find a lot of older threads about it.
If you were talking about something esle please clarify.