# Don't do this!
my @defeat_stream;
my $xls = Spreadsheet::ParseExcel::Stream->new($xls_file, \%options);
while ( my $sheet = $xls->sheet() ) {
     while ( my $row = $sheet->row ) {
         # current row now in memory.
         my @data = @$row;
         # after this, current row will *disappear*, unless...
         # you keep the data.
         push @defeat_stream, $row;
     }
}
# Now you either have the entire spreadsheet in memory (defeating the purpose
# of the module), or have run out of memory.