Ich glaub MAX_FILE_SIZE macht das ...
<form method="post" action="index.html" enctype="multipart/form-data">
<input type="hidden" name="MAX_FILE_SIZE" value="80000">
<input type="file" size="-1" class="inputimage" name="file">
<input type="image" name="button_saveimage_2" src="/imga/save.png" border="0" width="22" height="20" title="">
</form>
Geht zumindest bei multipart/form-data
Gruss