Yes, currently it means "stop". But then, "stop" didn't always mean "stop", if you know what I mean. (It originally meant, "to stop something up", and not "halt".)
If you look closely at the ashi kanji, you'll notice that below the box is the kanji for tomeru! You see, the 止 character was originally a pictorgraph of foot, specifically a footprint. Look at the character for "walk" 歩, and you can see the character at the top representing one footstep, while the character below represents the other foot, hence, "walking".
Because 止 represented a footprint, it took on the sense of standing still (enough to leave a print), and from that, to stop, halt. To represent foot, then, 足 was created. This character, incidently, means "foot", not leg. The character for leg, also read ashi is actually 脚.
In general, it's best not to assume that component kanji parts mean what their individual characters mean, as there as been both linguistic shift in Chinese and Japanese, as well as orthographic shift in the kanji. For example, one may look at the kanji for shoulder 肩, and see "door" 戸 and "moon" 月. Hmmm, how did the Chinese get "shoulder" from a door on the moon?! But in fact, what looks like 戸 is actually a pictograph representing the skeletal structure from the collarbone down the arm, and what looks like 月 is actually a reduced form of 肉, "flesh".