cupboard, pantry, to store
庋 centers on a place for keeping things: a cupboard, pantry, or the act of storing items away.
庋 combines 广 (building or roof) with 支, which likely contributes the sound. The exact historical development is uncertain.
Under a roof 广, a hand 支 stores things away in a cupboard or pantry.
For キ, imagine a key unlocking a cupboard: key -> キ, and the hand stores items inside.