Oracle Database Discussions

While running a batch job we get below error in database.

"ORA-12801: error signaled in parallel query server P249, instance derintoin:hint1 (1)
ORA-12853: insufficient memory for PX buffers: current 1552016K, max needed 6500304K
ORA-04031: unable to all"

Oracle Database version --11.2.0.1.0

SGA is set to 8gb but memory parameters are set to 0

SQL> show parameter sga

NAME TYPE VALUE
--------------- -------------------------------- -------
sga_max_size big integer 8G
sga_target big integer 8G


SQL> show parameter memory

NAME TYPE VALUE
---------------------- ---------------- ------
memory_max_target big integer 0
memory_target big integer 0

There are totally 10 databases are running in the server.
Memory size:126gb
Number of CPU -- 48

Please advice me whether i should increase memory parameters or sga parameters to resolve the error.If i have to increase memory ,please advice how much i should increase .

Thank you