Pocket kings (KK) is the second-best starting hand in hold 'em, and as such, should be played pre-flop and post-flop like AA. The idea behind preflop raises is to build pot equity and clear the field of drawing hands. With KK, the holder also wants to chase out weak aces (generally, A-2 through A-6, the holders of which may fear they are up against a stronger ace and fold) and narrow the opposition down to strong aces (AK, AQ, AJ, A10), other big unpaired cards, and lower pocket pairs. As with AA, the nature of limit hold 'em restricts the holder from clearing the field as effectively as she could in no-limit, so attention must be paid to the possibility of straight and flush draws and other superior hands after the flop.
|PokerWiki's guide to limit hold 'em preflop play|