In a large pot, bring the stock (or broth) to a boil. Add salt and sugar, stirring until they dissolve. Add the bay leaves, peppercorns, and allspice berries.
Remove the pot from the heat and allow the brine to cool to room temperature.
Remove the giblets and neck from the turkey cavity. Pat it dry with paper towels.
Place the turkey into a clean, food-grade plastic container, pot, or brining bag. Make sure it's large enough to hold the turkey and the brine solution.
Pour the cooled brine along with the ice water over the turkey, making sure it's fully submerged. If the turkey is floating, you can use a heavy plate or a bag of ice to keep it submerged.
Add fresh rosemary, thyme, and sage sprigs to the turkey and brine.
Seal the bag or cover the container and place it in the refrigerator.
Brine the turkey for approximately 1 hour per pound, but not less than 12 hours and not more than 24 hours. Longer brining can make the turkey too salty. Turn the bird once halfway through brining. You can also use a cooler with ice packs to keep it at a safe temperature if your refrigerator doesn't have enough room.
After the brining period is complete, remove the turkey from the brine. Discard the brine. Note: there is no need to wash the turkey before cooking.
The turkey is ready to be roasted, smoked, grilled, or prepared according to your favorite recipe.