Hmmm - I tried this:

#!/usr/bin/perl -w

use strict;

use DBI;

my $dbh = DBI->connect('dbi:Sybase:host=somehost;port=4100', 'sa', '',
               { syb_err_handler => sub { print "@_\n"; } });

$dbh->do("sp_dbcc_recommendations testdb");
[download]

and got

0 10 1 237 gndb2 sp_dbcc_run_recommendations The checkstorage run corr
+esponding to dbid '4', opid '2', reported no faults; therefore, no co
+rrective action is necessary. sp_dbcc_recommendations smlive server
The checkstorage run corresponding to dbid '4', opid '2', reported no 
+faults; therefore, no corrective action is necessary.
[download]

Admittedly this is on a 12.5.0.3 server, so you may get different output.

Try running with DBI->trace(3) - that should give you all of the outputs from the server in the trace file (stderr by default). You can then try to see what the problem is.

Michael