$ cat .SQL/glark.pks
create or replace package glark as
function gragnar(t in date, TZ1 in varchar2, TZ2 in varchar2)
    return timestamp with local time zone;
end glark;

$ cat .SQL/glark.pkb
create or replace package body glark as
    function gragnar(t in date, TZ1 in varchar2, TZ2 in varchar2)
        return timestamp with local time zone
    is
        retval timestamp with local time zone;
    begin
        select (from_tz(cast(t as timestamp), TZ1) at time zone TZ2) into retval from dual;
        return retval;
    end gragnar;
end glark;

$ cat t.pl
#/usr/bin/perl
use strict;
use warnings;
use feature ':5.10';
use XYZ::DBASE;
use XYZ::Utils qw(dump_query);

my $DB = XYZ::DBASE::connect('XYZDEV');
my $ST = $DB->prepare(<<SQL);
select glark.gragnar(sysdate, :T, :U) from dual
SQL
$ST->bind_param(':T', 'Europe/Berlin');
$ST->bind_param(':U', 'Europe/Berlin');
$ST->execute;
dump_query($ST);

$ perl t.pl
DBD::Oracle::st fetchall_arrayref failed: ORA-00923: FROM keyword not found where expected
ORA-06512: at "DEV_ROBO.GLARK", line 7 (DBD ERROR: OCIStmtFetch) [for Statement "select glark.gragnar(sysdate, :T, :U) from dual
" with ParamValues: :t='Europe/Berlin', :u='Europe/Berlin'] at /Work/Perl/LIB/XYZ/Utils.pm line 342.

##</code><code>##

select * from v$version
BANNER
----------------------------------------------------------------
Oracle9i Enterprise Edition Release 9.2.0.7.0 - 64bit Production
PL/SQL Release 9.2.0.7.0 - Production
CORE9.2.0.7.0Production
TNS for Linux: Version 9.2.0.7.0 - Production
NLSRTL Version 9.2.0.7.0 - Production

5 rows
elapsed time: 0