I'd like to
diff large files in vim using the scrollback limit set in my terminal (which is available memory), so I can, if necessary, find and review previously applied changes.
I use OS X's Terminal set to
alternate screen is disabled).
I couldn't find any settings to make the initial windows the same size as the opened files.
A workaround for single files is using MouseTerm to enable mouse reporting, then add to your
if has("mouse") set mouse=a endif
vimdiff this allows to easily scroll long files, but the text is not kept in the scrollback, although it does for single files.