C:\test>perl -wle "$x='' x 1024 x 1024 x 256; print length( $x )"
0

##</code><code>##

C:\test>perl -wle "$x = chr(0) x 1024 x 1024 x 256; print length( $x )"
268435456

##</code><code>##

C:\test>perl -wle "$x = chr(0) x (1024* 1024 * 256); print length( $x );<>"
268435456