Memory Pressure and its resolutions

1. How much space been occupied by single adhoc plans?
The below query would give you information about how much space been used for single adhoc. This is a wastage of memeory.
We can think of some useful setting at server level to have Optimize for adhoc settings.
Optimize for adhoc will never save the cache plan until it is been used for the second time. First time, it saves only the plan stub in the memeory.
Second time execution, it uses the same plan stub and save the cached plan in the memeory.To me this is a very good option that we can think of.

/**************************Check Optimize for Adhoc settings**********************************/
SELECT objtype AS [CacheType]
        , count_big(*) AS [Total Plans]
        , sum(cast(size_in_bytes as decimal(12,2)))/1024/1024 AS [Total MBs]
        , avg(usecounts) AS [Avg Use Count]
        , sum(cast((CASE WHEN usecounts = 1 THEN size_in_bytes ELSE 0 END) as decimal(12,2)))/1024/1024 AS [Total MBs - USE Count 1]
        , sum(CASE WHEN usecounts = 1 THEN 1 ELSE 0 END) AS [Total Plans - USE Count 1]
FROM sys.dm_exec_cached_plans
GROUP BY objtype
ORDER BY [Total MBs - USE Count 1] DESC
go

--Total Size of the procedure cache
SELECT SUM(CAST(size_in_bytes AS BIGINT))/1024/1024 AS 'Size (MB)'
FROM sys.dm_exec_cached_plans;

--Break up of procedure cache utilization
SELECT objtype AS 'Type',
COUNT(*) AS '# Plans',
SUM(CAST(size_in_bytes AS BIGINT))/1024/1024 AS 'Size (MB)',
AVG(usecounts) AS 'Avg uses'
FROM sys.dm_exec_cached_plans
GROUP BY objtype;

--Total size used for single use adhocs
SELECT SUM(CAST(size_in_bytes AS BIGINT))/1024/1024 AS 'Size (MB)'
FROM sys.dm_exec_cached_plans
WHERE objtype = 'Adhoc' AND usecounts = 1;
/**************************Check Optimize for Adhoc settings**********************************/

Setting Optimize for Adhoc, follow the below steps:
Look at sp_configure for "optimize for ad hoc workloads"
Exec sp_configure

Set the value as 1
sp_configure 'optimize for ad hoc workloads',1