AMM & PGA_AGGREGATE_TARGET

SQL> show parameter target

memory_max_target                    big integer 3488M

memory_target                        big integer 2880M

pga_aggregate_target                 big integer 64M

SQL> select value, unit from v$pgastat where name='maximum PGA allocated';

     VALUE UNIT

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

884808704 bytes

Please suggest if I change pga_aggregate_target to 844MB? (884808704/1024/1024)?

Do I make pga_aggregate_target 0 and let oracle decide on it dynamically?

Sicere thanks in advance.