Top-and-left wrap component - a measuring ruler. In 局 it depicts something framed, bounded, measured-out: a confined space. Reads as 尺 wrapping the 口 below into a defined area. The entry's indexing radical is Kangxi #44 尸 (corpse) - the top portion of 尺 - used purely for dictionary lookup rather than meaning.
Inner 口 - a small enclosed space, here representing the bounded room or office that 尺 above marks out. The compound ideograph reads 'measured-out enclosure' - a confined chamber, a bureau, a chess game played within a marked board. From this came the modern senses: bureau (邮局 post office), situation (局面), chess game (棋局), bounded role (局长 bureau chief).
Filed under radical 尸 (shī, #44) by convention. 尸 is not a separate component in 局, so no strokes are highlighted.
