my %all_files;

foreach my $file (@files) {
    open(my $fh, "<", $file);
    my @data = <$fh>;
    $all_files{$file} = \@data;
    close($fh);
}

##</code><code>##

foreach my $file (@files) {
    open(my $fh, "<", $file;
    my @data = <$fh>;
    close($fh);
}

##</code><code>##

{
   my @file;
   my $fh;
   foreach my $file (@files) {
       open($fh, "<", $file);
       @data = <$fh>;
       close($fh);
       undef $fh;   # Frees $fh's content.
       undef @data; # Frees @data's content.
   }
}