SQL> alter session set max_dump_file_size = unlimited timed_statistics = true session_cached_cursors
 = 1500 tracefile_identifier = 'ARP_20120806_1' events = '10053 trace name context forever, level 1'
;

Session altered.

Elapsed: 00:00:00.00
SQL> set termout off
SQL> set serveroutput on
SQL> set timing on
SQL>
SQL> select count(*) from dba_objects;

  COUNT(*)
----------
    135930

1 row selected.

Elapsed: 00:00:00.37
SQL> alter session set session_cached_cursors = 0;

Session altered.

Elapsed: 00:00:00.00
SQL> alter session set events = '10053 trace name context off';

Session altered.

Elapsed: 00:00:00.00
SQL>
SQL>
SQL> set termout on
SQL>
SQL> SELECT VALUE FROM V$DIAG_INFO WHERE NAME = 'Default Trace File';

VALUE
----------------------------------------------------------------------------------------------------
--------------------------------------------------
Z:\oracle\........\some_db_ora_1820_ARP_20120806_1.trc

1 row selected.

Elapsed: 00:00:00.04
SQL>