MAC Storage

 is a generic United Nations Space Command term for either of the two area on an Orbital Magnetic Accelerator Cannon Platform between the armories and Firing Control where MAC rounds are stored.

Cairo Station MAC Storage
Cairo Station MAC Storage refers to the area below Armory A-01 where MAC rounds are stored. During the First Battle of Earth, SPARTAN-117 went through MAC Storage to get to the Armory, where he avenged the unnamed Master Gunnery Sergeant's death before moving on to Commons B-01.