parallel hint doesn't start parallel processing

Hi,

I am using parallel hint in my SQL but system doesn't generate parallel salves. Do I need to enable any parameter at database level to get parallel processes?

for example if I run below SQL, it doesn't create any slave process.

insert /*+ PARALLEL(a,16)*/ into test a select * from dba_tables;

SQL> show parameter parallel;

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

fast_start_parallel_rollback         string      LOW

parallel_adaptive_multi_user         boolean     TRUE

parallel_automatic_tuning            boolean     FALSE

parallel_execution_message_size      integer     2152

parallel_instance_group              string

parallel_max_servers                 integer     135

parallel_min_percent                 integer     0

parallel_min_servers                 integer     0