The liquid can be used for soup.
I freeze mine in 3 cup containers.
A woman named Jen from my MOMS club told me about this crockpot stock years ago and I have been doing it ever since. I feel better using the entire chicken.
Warning: When I used to do this at night, I could smell it cooking and I got so hungry. Now I always make my stock during the day!
Note: I read recently that stock cooked for a long time can be healthier for you as minerals and other nutrients leach from the bones into the water. Homemade broth is rich in calcium, magnesium, phosphorus and other trace minerals! You might need to add apple cider vinegar to get the minerals out.
Stephanie O'Dea has several other crockpot stock recipes on her blog: http://crockpot365.blogspot.com/2011/04/how-to-make-vegetable-broth-using-your.html and http://crockpot365.blogspot.com/2008/05/homemade-beef-stock-in-crockpot.html