What are your OS, Perl and Oracle versions ?

I am using Windows7. Now I am using connectstring that you have provided, and included to_char on top of timestamp. but I still get same error.

DBD::Oracle::st execute failed: ORA-06502: PL/SQL: numeric or value error: chara cter string buffer too small ORA-06512: at line 1 (DBD ERROR: OCIStmtExecute) for Statement "BEGIN :now := TO_CHAR(CURRENT_TIMESTAMP) ; END;" with ParamValues: :now='' at t.pl line 16.

Try this modified code. Procedures don't have to return values but I have done it in these examples to show the procedure is being executed.

#!perl
use strict;
use DBD::Oracle;
use DBD::Oracle qw(:ora_types);

runNoReturn("BEGIN NULL; END;");

runAndReturn("BEGIN :out := CONCAT('Hello ',USER) ; END;");
runAndReturn("BEGIN :out := CURRENT_DATE ; END;");
runAndReturn("
  BEGIN
    :out := TO_CHAR (SYSDATE, 'DD-MON-YYYY HH24:MI:SS'); 
  END;");

sub runNoReturn { 
  my $procT = shift;
  my $dbh1=DBI->connect(
    'dbi:Oracle:host=localhost;sid=xe','user','pwd', 
    {RaiseError => 1 , PrintError => 0} );     
   
  $dbh1->do($procT);   
  $dbh1->disconnect; 
  print "Anon $procT finished\n";
} 

         
sub runAndReturn { 
  my $procT = shift;
  my $dbh1=DBI->connect(
    'dbi:Oracle:host=localhost;sid=xe','user','pwd', 
      {RaiseError => 1 , PrintError => 0} );     
   
  my $out  = '';   
  my $sth1 = $dbh1->prepare($procT); 
   
  $sth1->bind_param_inout(":out",\$out,50,{ora_type => ORA_VARCHAR2});
  $sth1->execute;
  $dbh1->disconnect; 
  print "$out\n";
}
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poj

OS is windows 7, perl v5.16.3 and Oracle is 11g

Ok, are you using ODBC ?

Try

runThis("BEGIN :now  := TO_CHAR(CURRENT_TIMESTAMP) ; END;");