my @data = prepData();

for my $item (@data) {
    #format and output
}

sub prepData {
    my @data;
    #create array of hashes
    return @data;
}

##</code><code>##

my @data;
prepData(\@data);
for my $item (@data) {
    #format and output
}
sub prepData {
   my $refData = shift;
   #do data generation;
}

##</code><code>##

my $refData = prepData();
for my $item (@$refData) {
   #format and output
}
sub prepData {
    my @data;
    #create array of hashes
    return \@data;
}