LARGE_POOL_SIZE

Property	Description
Parameter type	Big integer
Syntax	`LARGE_POOL_SIZE =` `integer` `[K \| M \| G]`
Default value	`0` if both of the following are true: The pool is not required by parallel execution `DBWR_IO_SLAVES` is not set Otherwise, derived from the values of `PARALLEL_MAX_SERVERS`, `PARALLEL_THREADS_PER_CPU`, `CLUSTER_DATABASE_INSTANCES`, `DISPATCHERS`, and `DBWR_IO_SLAVES`. Note that a value derived in this way does not take into account the requirements used for Automatic Storage Management files. As a general guideline, you should add 600K to the size of the SGA on a database instance using ASM.
Modifiable	`ALTER SYSTEM`
Range of values	300 KB to at least 2 GB (actual maximum is operating system-specific)
Basic	No

LARGE_POOL_SIZE specifies (in bytes) the size of the large pool allocation heap. The large pool allocation heap is used in shared server systems for session memory, by parallel execution for message buffers, and by backup processes for disk I/O buffers. Parallel execution allocates buffers out of the large pool only when PARALLEL_AUTOMATIC_TUNING is set to true. Note that the PARALLEL_AUTOMATIC_TUNING parameter has been deprecated.

Caution:

When Oracle derives a default value, it adds 250K for each session for the shared server if DISPATCHERS is configured. The final derived value also includes a port-specific amount of memory for backup I/O buffers. The total derived default value can either be too large to allocate or can cause performance problems. In that case, set LARGE_POOL_SIZE to a number sufficiently small so that the database can start.

You can specify the value of this parameter using a number, optionally followed by K or M to specify kilobytes or megabytes, respectively. If you do not specify K or M, then the number is taken as bytes.