Place chicken carcass, and extra chicken pieces (if using), into a large stock pot.
Add vegetables, seasonings, and salt (if using) and cover with 8-9 cups of cold water.
Using medium heat, bring the pot to a boil, then immediately turn it down to low, for a very subtle simmer.
Simmer on low for 2-3 hours. Let cool, then strain into a container using a mesh strainer.
This stock will stay in an airtight container for 4-5 days in the refrigerator or up to 6months in the freezer. Remember to simmer the stock over low heat before using it!