Changing stage height

I have a main movieclip that contains many instances of another type movie clip(say B). teh main mc is dropped on the main timline.
I want to increase stage height thru actionscript dynamically if i have more number f type B mclps…

If i use _height on main timleine it widens teh type B mclips too.
how do i increase only the stage height?
I tried _xscale property also, but no way.

I’d appreciate any help…

Your main movie determines the stage size.

If you want to give the illusion of the stage changing size, think of it this way:

add a layer on the bottom, with a portion of the stage covered with the same color as your background…

Then through AS, change the size of that “mask”, and it will look like your stage size has changed…