It's good to see you using use strict;. However you only need it once in your script (although may be this is a couple of scripts combined to show the issue, in which case good work and ignore the comment).

I recommend that you return as soon as you find and deal with an error so you don't clutter the following code with redundant tests:

   if ($paramno == 0) {
      print "\n\tNo parameters supplied - can't set up environment!\n"
+ ;
      return 0;
   }
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However the real problem seems to be that you are creating an array containing a single element which is a reference to a hash in your lookup hash, where I suspect you really just want a reference thus:

   my %DBhashlookup = (
   "TEST"      =>  \%TEST,
   "LIVE"      =>  \%LIVE,
   "DEVLP"     =>  \%DEVLP,
   ) ;
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Making that change and running the code prints:

    xxrctest S T A R T S

    KEY    ::  ADMIN_DIR

    VALUE  ::  /opt/bin2

    xxrctest E N D S
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