It nests! So you won't need 32 pieces of room.
The point of Pyrex is to take up space. Pyrex makes a reasonable shield around the food you want to save, trapping in the stuff you want later and trapping out the forces of decay. But when you're not using the Pyrex, you don't want that space to work the same way! You want to keep that space for better things! So don't worry. The Pyrex can stack. It's like 32 pieces in a 15 piece space or whatever. We're just estimating, really. Don't hold us to our answer.