my %stacks = ( A => [],
               B => [],
                  .
                  .
                  .
               Z => [],
             );

# microseconds later...

my $current_stack = $stacks{ K };  # for example

push @$current_stack, 'whatever';

# etc.;

##</code><code>##

my %stacks; @stacks{ @names } = map [], @names;

##</code><code>##