textbox size at runtime

Hi...
im working on a project ive tried couple of things to do the work but none of them work really the way i want them to so...

i was wondering if u could set a textbox's height based on the number of characters or something, wha tim trying to say is,  i have a multiline textbox with the scrollbar disabled, however i want the textbox to display multilined stuff without having to scroll and without setting a definite size, the textbox adjusts its height (only height, width is static) based on the string being displayed without anything being outside the size of the textbox which would cause the user to scroll
ive tried setting the textbox height="100%" however when i place it in a div tag and display the page, since the div tag has a height of auto it will not change unless something if oversize, and the textbox will not expand the div tag because it uses percentile to fill it up... so there is a bit of conflict going on

if anyone could help me, much appreciated...