These may be specified in pixels:

style='height:80px'

Or they may be specified as a fraction of the space available:

width=80%

And they may be combined:

<frame
name="top_of_page_banner"
style=height:80px
width=100%
src="banner.html"
>

<frame
name="left_side_navbar"
height:100%
width=120px
src="navbar.html"
>