First, place the chicken carcasses into the instant pot (mine is a 6 quart). Next cut the washed carrots and celery into two inch pieces and toss into the instant pot. Cut both ends from a large onion (white, yellow or purple onion will work). Add the peppercorns and parley to the instant pot. Lastly, fill the instant pot to the 2/3 fill line for one chicken carcass or the top fill line for two carcasses. Secure the lid and set to the soup setting for 90 minutes. Once finished, allow the Instant Pot to slow release. Remove the insert from the pot and allow to cool for several hours. Place a large bowl (with a spout or use a funnel when ready to pour) with a large strainer inside of the bowl. Pour all of the contents from the Instant Pot into the bowl lined with a strainer. Lift up the strainer until the liquid is finished draining. Pour the stock into glass mason jars to freeze, or leave in the bowl to cool completely before refrigerating or freezing. 

The stock is now ready to use in soups, stews, rice, or sipping!