Place about 2 lbs. chicken carcasses or bones in a large saucepan.  Cover with 12 cups water.  Add 2 chopped onions, 2 sliced carrots, a handful of celery leaves, 1 bay leaf and 1 tsp. salt.  Bring to a boil, then reduce heat and simmer, covered, about 3 hours.  Stir occasionally and skim off the surface.

Strain the stock through a sieve and refrigerate.  When cool, skim off the fat and discard.  Store, covered, in the refrigerator for several days or in the freezer.