use warnings;
use strict;
use File::Slurp;

my %data;
for (glob '*') {
    push @{ $data{$_} }, read_file($_);
}
[download]

See also:

• glob
• perldsc
• File::Slurp

Same with array-of-arrays:

my @data;
for (glob '*') {
    push @data, [ read_file($_) ];
}
[download]

bash-3.2$ cat d1      
abc
cde
edf
bash-3.2$ cat d2
rst
tuv
uvw
bash-3.2$ cat d3
ghi
hij
jkl
bash-3.2$ cat t4.pl
my %data;

while (<>)
{
    chomp;
    push @{ $data{$ARGV} }, $_;
}

my @sorted_data = map $data{$_}, sort keys %data;

use Data::Dumper;
warn Dumper \@sorted_data;

bash-3.2$ t4.pl *
$VAR1 = [
          [
            'abc',
            'cde',
            'edf'
          ],
          [
            'rst',
            'tuv',
            'uvw'
          ],
          [
            'ghi',
            'hij',
            'jkl'
          ]
        ];
[download]

if I do it thru a reference the content will change in the next loop when I modify @currentFile again

Don't define @currentfile in that scope then.

my @combinedData;
my @filesList = <*>;

foreach my $file (@filesList) {
   my @currentFile;
   open(F, "file.txt") or die("Unable to open file");
   @currentFile = <F>;

   # HOW TO COMBINE IT INTO @combinedData ?
   push @combinedData, \@currentFile;
}
[download]