Place all ingredients, except for parsley and salt & pepper, in a large stock pot.
Heat to a light boil, then adjust the burner so the stock remains at a low simmer. Simmer for 24 hours or more, checking once in a while to make sure you're not losing water. Add more water if needed.
Half an hour before the stock is done, add the parsley.
Using a large slotted spoon, remove bones, meat and vegetables. Strain stock through a fine mesh sieve or cheese cloth if desired. Add salt & pepper.
If you find it necessary, let stock cool in refrigerator to solidify fat for removal (chicken stock usually has less fat than beef). You can refrigerate the pot if you have room, or if you plan to freeze the stock, you can put the stock in jars and put them in the refrigerator. Otherwise...
Freeze jars or pressure can per your canner's instructions (this would entail reheating the stock).