You do not have to set a value for the LARGE_POOL_SIZE initialization parameter if you use automatic memory management.
The setting for the LARGE_POOL_SIZE parameter is used for large allocations. The default value for this parameter is suitable for most environments.
Oracle Database Administrator's Guide for more information about setting the LARGE_POOL_SIZE initialization parameter
Oracle Database Performance Tuning Guide for more information about memory configuration
Oracle Database Reference for more information about the LARGE_POOL_SIZE parameter