To Check Memory Usage for Plan Cache

select name, type, buckets_count from sys.dm_os_memory_cache_hash_tables where name IN ( 'SQL Plans' , 'Object Plans' , 'Bound Trees' ,'Extended Stored Procedures')

select name, type, pages_kb, entries_count from sys.dm_os_memory_cache_counters where name IN ( 'SQL Plans' , 'Object Plans' , 'Bound Trees' ,'Extended Stored Procedures')