Start with a clean 23 quart pressure canner. Add all the chicken pieces, carrots, celery, onions, garlic, salt and peppercorns to the pot.
Add water till your pot is 2/3 full. Place lid on the canner and twist till closed.
Place the regulator on immediately, turn on the heat, and bring it up to 15 lbs of pressure.
Hold at 15 lbs of pressure for 10 minutes.
Turn the heat off and allow the pressure to drop. Once the pressure has dropped open the lid and let the stock cool a bit (I normally let it sit for an hour or so. It is rip roaring hot).
Strain stock into a cheesecloth lined colander set over a bowl. Use a couple of bowls if necessary.
Allow to cool overnight in the fridge.
Skim off the fat and discard. Scoop or pour (depending on much the stock gelled) in to storage containers.
Freeze for up to 1 year. If it lasts that long.
Notes
Note: These are the instructions based on my pressure canner. The pounds of pressure and times are based on the instruction for a Presto 23-Quart Pressure Canner and Cooker. Please check and follow the directions for your canner.