How about...

use IO::File ();
my $fh = IO::File->new($filename,'r');

### slurp it in
my $txt;
read($fh,$txt,-s $filename);

my $LS = ($txt=~s/^(LINESCORE(.+?)\n\r?\n)//s) 
  ? $1 : '';
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And now you have it. The other way is to read the file a line at a time and using sentinels funnel the information into two different variables.