%hashlist =();

foreach key1,key2,key3

do

$hashlist->{key1,key2,key3}++;

and to list the occurences of such a hash i do,

foreach $key(keys %hashlist)

{

     ($dim1,$dim2,$dim3) = (split %;, $key)[0,1,2];

     print "$hashlist->{dim0} ";

}