Albert Barnes Commentary 1 Kings 8:64

"The same day did the king hallow the middle of the court that was before the house of Jehovah; for there he offered the burnt-offering, and the meal-offering, and the fat of the peace-offerings, because the brazen altar that was before Jehovah was too little to receive the burnt-offering, and the meal-offering, and the fat of the peace-offerings." — 1 Kings 8:64 (ASV)

The middle of the court—or, "the whole area of the court"—refers to the entire "mid" space within the enclosing walls. This area thus became one huge altar, on any part of which victims could be offered at the same time.