IFRAME fitting in a window

[Raja Kannan]

I have three IFRAME in a page as below,

<IFRAME name="top" src="<%= response.encodeURL("Top.jsp") %>"
align=top scrolling="no" marginHeight="0" marginWidth="0"
APPLICATION="yes" frameborder=0
style="width:expression(screen.width);height:100px;">
</IFRAME>
<IFRAME name="middle" src="<%= response.encodeURL("middle.jsp")%>"
height= "????" marginHeight="0" marginWidth="0" align=absbottom
width="100%" APPLICATION="yes" frameborder=0 >
</IFRAME>
<IFRAME name="bottom" src="<%=
response.encodeURL("Advertise.jsp.jsp")%>" height="60" width="100%"
marginHeight="2" marginWidth="0" scrolling="no" APPLICATION="yes"
frameborder=0 style="vertical-align: text-bottom">
</IFRAME>

the top frame size is 100px and the bottom frame size is 60px and
iwant to leave the reaming to the middle frame height , how do i find
, it needs to work of window is resized and on any resolution.

any help would be appreciated.