Well, the documentation states that these new columns were added from SQL 2016. However, they are available in my SQL 2014 instance.
SELECT @@VERSION;
Microsoft SQL Server 2014 (SP2-GDR) (KB3194714) - 12.0.5203.0 (X64)
Sep 23 2016 18:13:56
Copyright (c) Microsoft Corporation
Developer Edition (64-bit) on Windows NT 6.1 <X64> (Build 7601: Service Pack 1)
select
total_dop
, total_reserved_threads
, total_grant_kb
from sys.dm_exec_query_stats;
total_dop total_reserved_threads total_grant_kb
3 0 3072
1 0 1872
1 0 1024