When I first started making my own stock, all types, I used to freeze it in quart size containers. But, more often than not, all I needed was a cup, or a half cup, or even just a few tablespoons of super rich beef stock.
Finally, one day, I had made a delicious beef stock. I let reduce a lot, and then, I poured it into an ice cube tray for freezing. I used to make C’s baby food and freeze it this way. It was super convenient to be able to pull out a few ice cubes and let them thaw for one meal.
So, thereafter, I have taken to freezing stock (usually chicken), in a muffin tin, popping them out the next day and transferring them to a large ziploc bag. Each frozen “muffin” is about a half cup, perfect for enriching gravies, cream sauces, and also adding to stir-fries. C’s favorite is Beef & Broccoli, which is always better with a few tablespoons of beef or chicken stock instead of all soy sauce.
Hope this helps!