Whenever I roast or grill a chicken, I freeze the carcass along with any trimmings.  When I trim and bone chicken breasts and thighs, I freeze all the bits and pieces, also.  And, I save any necks or wing tips that come my way.  Then, when the spirit moves me or when my supply of frozen chicken stock is diminishing, I throw the collection of carcasses along with the bits and pieces into the stock pot – no need to thaw.  I add a big onion (including the skin) with a clove or two stuck into it, a couple of chopped carrots, a stalk or two of celery cut into chunks, parsley stems (which I also pull from the freezer), and, if there is still some in the freezer, any remaining chicken stock from the last batch.  I add a couple of gallons of cold water and bring the mix to a boil over high heat.  I add some salt and peppercorns, lower the heat to a nice, gentle simmer (this is important because if the stock boils, you will end up with a fraction of the amount and it will be shallow and salty), and go about my business.  After 3 or 4 hours (or, if I get distracted 5 or 6 hours), I pull the pot off the stove and let it cool for about 30 minutes.  I then strain the liquid through a fine mesh sieve, discarding all of the solids.  I place the stock in an ice bath to cool it down rapidly.  Then, I ladle about 2 cups into as many small, resealable freezer bags as it will produce.  I also fill an ice cube tray or two with stock so that I can have small amounts at the ready when I need them.  They all go in the freezer and whenever I need it, I have a deep, dark, rich chicken stock to use in soups, sauces, and stews.