my @p;
sub part
{
   my ($a, $k, $n, $t) = @_;
   $n = 2*$k unless (defined($n));
   $t = 0    unless (defined($t));
   $p[$t] = $k;
   push(@$a, [ @p[1..$#p] ]) if $n == $k;
   for (my $j = $k<$n-$k ? $k : $n-$k; $j >= 1; $j--) {
      part($a, $j, $n-$k, $t+1);
   }
}


my $integer = ...;
my @a;
part(\@a, $integer);
print(join(" ", @$_), "\n") foreach (@a);
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Depending on what you're doing, you should reconsider your desire to keep this data in an array. As n grows, the data requirements for that array grow rapidly. Once you use up available RAM (which happens sooner than you'd think), you're in trouble.

Changing your flow of control of your actual problem to avoid having to have it all in memory at once will let you calculate several more values of whatever you're trying to calculate.