SGA POOL Size

SELECT pool, SUM(ROUND(bytes/(1024*1024),2)) || ' MB' "SIZE"
FROM (SELECT DECODE(pool, NULL, NAME, pool) pool, NAME, BYTES    FROM v$sgastat) v$sgastat
GROUP BY pool;

To see init parameters about sga pools:

SELECT * FROM v$parameter 
WHERE NAME IN('db_cache_size', 'java_pool_size', 'large_pool_size', 'log_buffer', 
'shared_pool_size', 'shared_pool_reserved_size', 'sga_max_size', 'sga_target', 'pre_page_sga', 
'lock_sga');