Welcome to FT!
It would be helpful to know which airline(s) you are flying.
But if you have one ticket, then 1:40 should be doable. If your bags are checked all the way through to Anchorage, then you will just go through security. No need to go out (through immigration/border control) and come back in again.
Can I suggest you read this thread http://www.flyertalk.com/forum/miles...on-thread.html from the Lufthansa forum, particularly the first post which describes all the connection options and routes at Frankfurt.