my $header = "";
$header .= <$TEXTIN> for 0..1; # record the first two lines for later use
while(<$TEXTIN>){
     next if m/^\s*$/; # get rid of empty lines
     if (m{$rxRecStart}){
          # do what you need to finish off the previous section
          # (saving the data) and start the new one
     } else {
         $recordStr .= $_;
     }
}
# add code here for storing the last section