Aligning to Top

Is it possible to force movieclips to be aligned to the top of your swf? but not have them overlap, so they stack underneath?

For example, i have 4 movie clips on my stage, the stage is 800px tall. the movie clips are about 150px tall. How through actionscripting how would i force them so that the top movieclip aligns to the top of the stage, and then the rest align directly under it?

The 4 movieclips are also dynamically re-arrangeable. You can drag them into a different order.