in reply to xls file number of reads limit?

What's the scope of @corners_xls and $counter_corners_xls? Aren't you creating an array of 3_000_000_000 elements?
map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]