I thought more about it and came up with this:
When you do the reservation in the clickie the stack that you have gets "frozen" in your inventory, if you collect more of the same a new stack is started, if the other player fulfills the requirements the "frozen" stack gets removed from your inventory and the player gets the reward, if the player that you addressed the stack to doesnt pick it up the stack disappears after 30 days.
When you do the reservation in the clickie the stack that you have gets "locked"(you cant give it to anyone else) in your inventory, if you collect more of the same it gets added to the stack, if the other player fulfills the requirements the "locked" stack gets removed from your inventory and the player gets the reward, if the player that you addressed the stack to doesnt pick it up the stack disappears after 30 days.
yes both are very similar, freezing and locking them might spare you of coding a storage type clickie since the stacks remain in the inventories