CREATE TABLE Stocks(ItemId int, SectorNo int, Level int, Plase int, InUse bit);
INSERT Stocks(ItemId,SectorNo,Level,Plase,InUse) VALUES
 (1 ,1 ,1 ,1 ,0)
,(2 ,1 ,1 ,2 ,0)
,(3 ,1 ,1 ,3 ,0)
,(4 ,1 ,1 ,4 ,1)
,(5 ,1 ,2 ,1 ,1)
,(6 ,1 ,2 ,2 ,1)
,(7 ,1 ,2 ,3 ,0)
,(8 ,1 ,2 ,4 ,0)
,(9 ,1 ,2 ,5 ,0)
,(10 ,1 ,2 ,6 ,0);

SELECT TOP 1 WITH TIES * FROM
(
 SELECT *,C=COUNT(*)OVER(PARTITION BY N,InUse)
 FROM(SELECT N=ROW_NUMBER()OVER(ORDER BY ItemId)-ROW_NUMBER()OVER(PARTITION BY InUse ORDER BY ItemId),* FROM Stocks)T
)T
WHERE InUse=0 AND C=3
ORDER BY N;

with d(ItemId, SectorNo, [Level], Place, InUse) as
(
	select 1, 1, 1, 1, 0 union all
	select 2, 1, 1, 2, 0 union all
	select 3, 1, 1, 3, 0 union all
	select 4, 1, 1, 4, 1 union all
	select 5, 1, 2, 1, 1 union all
	select 6, 1, 2, 2, 1 union all
	select 7, 1, 2, 3, 0 union all
	select 8, 1, 2, 4, 0 union all
	select 9, 1, 2, 5, 0 union all
	select 10, 1, 2, 6, 0
)
select *
from
(
	select *, count(case when InUse = 0 then 1 else null end) over (partition by SectorNo, [Level], g) as free_cnt
	from
	(
		select *, (row_number() over (partition by SectorNo, [Level] order by Place) - 
			row_number() over (partition by SectorNo, [Level], InUse order by Place)) as g
		from d
	) z
) q
where q.free_cnt = 3 --4

with d(ItemId, SectorNo, [Level], Place, InUse) as
(
	select 1, 1, 1, 1, 0 union all
	select 2, 1, 1, 2, 0 union all
	select 3, 1, 1, 3, 0 union all
	select 4, 1, 1, 4, 1 union all
	select 5, 1, 2, 1, 1 union all
	select 6, 1, 2, 2, 1 union all
	select 7, 1, 2, 3, 0 union all
	select 8, 1, 2, 4, 0 union all
	select 9, 1, 2, 5, 0 union all
	select 10, 1, 2, 6, 0
)
select stuff(
				(select top(4 /* тут параметр */) ',' + cast(ItemId as varchar)
				from
				(
					select *, count(case when InUse = 0 then 1 else null end) over (partition by SectorNo, [Level], g) as free_cnt
					from
					(
						select *, (row_number() over (partition by SectorNo, [Level] order by Place) - 
							row_number() over (partition by SectorNo, [Level], InUse order by Place)) as g
						from d
					) z
				) q
				where q.free_cnt >=4 /* тут параметр */
				order by g, SectorNo, [Level], Place
				for xml path('')), 1, 1, ''
			)

USE tempdb;
IF OBJECT_ID(N'Stocks',U) IS NOT NULL DROP TABLE Stocks;
CREATE TABLE Stocks(ItemId int, SectorNo int, Level int, Plase int, InUse bit);
INSERT Stocks(ItemId,SectorNo,Level,Plase,InUse) VALUES
 (1 ,1 ,1 ,1 ,0)
,(2 ,1 ,1 ,2 ,0)
,(3 ,1 ,1 ,3 ,0)
,(4 ,1 ,1 ,4 ,0)
,(5 ,1 ,2 ,1 ,1)
,(6 ,1 ,2 ,2 ,1)
,(7 ,1 ,2 ,3 ,1)
,(8 ,1 ,2 ,4 ,0)
,(9 ,1 ,2 ,5 ,0)
,(10 ,1 ,2 ,6 ,0);

SELECT TOP(3) * FROM
(
 SELECT TOP(1) WITH TIES * FROM
 (
  SELECT *,C=COUNT(*)OVER(PARTITION BY N,InUse)
  FROM(SELECT N=ROW_NUMBER()OVER(ORDER BY ItemId)-ROW_NUMBER()OVER(PARTITION BY InUse ORDER BY ItemId),* FROM Stocks)T
 )T
 WHERE InUse=0 AND C>=3
 ORDER BY N
)T
ORDER BY ItemId;

INSERT Stocks(ItemId,SectorNo,Level,Plase,InUse) VALUES
(1, 1, 1, 10, 0)
,(2, 1, 1, 12, 0)
,(3, 1, 1, 13, 0)

declare @size int

set @size = 4

; with t1 as (
select	s.ItemId,
		s.SectorNo,
		s.Level,
		s.Plase place,
		s.InUse,
		ROW_NUMBER() over (partition by s.sectorno, level order by plase) rn_place		
from Stocks s
where InUse = 0)
,t2 as (
select SectorNo, Level, MIN(place) place, COUNT(*) cnt
from t1
group by place - rn_place, sectorno, level
having COUNT(*) >= @size )
select top (@size) s.*
from t2
	inner join  Stocks s
		on t2.SectorNo = s.SectorNo
		 and t2.Level = s.Level
where s.Plase between t2.place and t2.place + @size - 1 
order by t2.SectorNo, t2.Level

INSERT Stocks(ItemId,SectorNo,Level,Plase,InUse) VALUES
(1, 1, 1, 10, 0)
,(2, 1, 1, 12, 0)
,(3, 1, 1, 13, 0)

with d(ItemId, SectorNo, [Level], Place, InUse) as
(
	select 1, 1, 1, 1, 0 union all
	select 2, 1, 1, 2, 0 union all
	select 3, 1, 1, 3, 0 union all
	select 4, 1, 1, 4, 1 union all
	select 5, 1, 2, 1, 1 union all
	select 6, 1, 2, 2, 1 union all
	select 7, 1, 2, 3, 0 union all
	select 8, 1, 2, 4, 0 union all
	select 9, 1, 2, 5, 0 union all
	select 10, 1, 2, 6, 0
)

select stuff(
				(select top(3 /* тут параметр */) ',' + cast(ItemId as varchar)
				from
				(
					select *, count(case when InUse = 0 then 1 else null end) over (partition by SectorNo, [Level], g) as free_cnt
					from
					(
						select *, (row_number() over (partition by SectorNo, [Level] order by Place) - 
							row_number() over (partition by SectorNo, [Level], place_iseland, InUse order by Place)) as g
						from
						(
							select *, Place - row_number() over(partition by SectORNo, [Level] order by Place) as place_iseland
							from d
						) m
					) z
				) q
				where q.free_cnt >=3 /* тут параметр */
				order by free_cnt, SectorNo, [Level], Place
				for xml path('')), 1, 1, ''
			)

declare @Stocks table (ItemId int, SectorNo int, [Level] int, Place int, InUse bit)
insert @Stocks values
	(1, 1, 1, 1, 1),(2, 1, 1, 2, 1),(3, 1, 1, 3, 0),(4, 1, 1, 4, 0),
	(5, 1, 2, 1, 0),(6, 1, 2, 2, 1),(7, 1, 2, 3, 0),(8, 1, 2, 4, 0),
	(9, 1, 2, 5, 0),(10,1, 2, 6, 0)

declare @SectorNo int, @Level int, @Place int, @InUse bit, @cnt int=0
declare @SectorNo2 int=0, @Level2 int=0, @Place2 int=0, @InUse2 bit=1

declare cStack cursor fast_forward for
select SectorNo, Level, Place, InUse from @Stocks order by SectorNo, Level, Place
open cStack
while 1=1 begin
   fetch next from cStack into @SectorNo, @Level, @Place, @InUse
if @@FETCH_STATUS!=0 break;
   if @SectorNo=@SectorNo2 and @Level=@Level2 and @InUse=0 /*and @Place=@Place2+1*/ begin
      select @cnt+=1 /*, @Place2=@Place */
      if @cnt>2 begin
         select * from @Stocks where SectorNo=@SectorNo and Level=@Level and Place in (@Place-2, @Place-1, @Place)
         break
      end
   end
   else
      select @cnt=0,@SectorNo2=@SectorNo, @Level2=@Level, @Place2=@Place
end
close cStack
deallocate cStack

with d(ItemId, SectorNo, [Level], Place, InUse) as
(
	select 1, 1, 1, 1, 0 union all
	select 2, 1, 1, 2, 0 union all
	select 3, 1, 1, 3, 0 union all
	select 4, 1, 1, 4, 1 union all
	select 5, 1, 2, 1, 1 union all
	select 6, 1, 2, 2, 1 union all
	select 7, 1, 2, 3, 0 union all
	select 8, 1, 2, 4, 0 union all
	select 9, 1, 2, 5, 0 union all
	select 10, 1, 2, 6, 0
)
select stuff(
				(select top(3 /* тут параметр */) ',' + cast(ItemId as varchar)
				from
				(
					select
						*,
						row_number() over(partition by SectorNo, [Level], g order by Place) +
							row_number() over(partition by SectorNo, [Level], g order by Place desc) - 1 as free_cnt

					from
					(
						select *, (row_number() over (partition by SectorNo, [Level] order by Place) - 
							row_number() over (partition by SectorNo, [Level], place_iseland, InUse order by Place)) as g
						from
						(
							select *, Place - row_number() over(partition by SectORNo, [Level] order by Place) as place_iseland
							from d
						) m
					) z
				) q
				where q.free_cnt >=3 /* тут параметр */
				order by free_cnt, SectorNo, [Level], Place
				for xml path('')), 1, 1, '')

with d as
(select * from (values
   (1, 1, 1, 1, 1),
   (2, 1, 1, 2, 1),
   (3, 1, 1, 3, 0),
   (4, 1, 1, 4, 0),
   (5, 1, 2, 1, 0),
   (6, 1, 2, 2, 1),
   (7, 1, 2, 3, 0),
   (8, 1, 2, 4, 0),
   (9, 1, 2, 5, 0),
   (10,1, 2, 6, 0)
   )d(ItemId, SectorNo, [Level], Place, InUse))

with d as
(select * from (values
   (1, 1, 1, 1, 1),
   (2, 1, 1, 2, 1),
   (3, 1, 1, 3, 0),
   (4, 1, 1, 4, 0),
   (5, 1, 2, 1, 0),
   (6, 1, 2, 2, 1),
   (7, 1, 2, 3, 0),
   (8, 1, 2, 4, 0),
   (9, 1, 2, 5, 0),
   (10,1, 2, 6, 0)
   )d(ItemId, SectorNo, [Level], Place, InUse))

with d as
(select * from (values
   (1, 1, 1, 1, 1),
   (2, 1, 1, 2, 1),
   (3, 1, 1, 3, 0),
   (4, 1, 1, 4, 0),
   (5, 1, 2, 1, 0),
   (6, 1, 2, 2, 1),
   (7, 1, 2, 3, 0),
   (8, 1, 2, 4, 0),
   (9, 1, 2, 5, 0),
   (10,1, 2, 6, 0)
   )d(ItemId, SectorNo, [Level], Place, InUse))
					
select stuff(
(
	select top(3 /* тут параметр */) ',' + cast(ItemId as varchar)
	from
	(
		select
			*,
			row_number() over(partition by SectorNo, [Level], InUse, g order by Place) +
				row_number() over(partition by SectorNo, [Level], InUse, g order by Place desc) - 1 as free_cnt

		from
		(
			select *, (row_number() over (partition by SectorNo, [Level] order by Place) - 
				row_number() over (partition by SectorNo, [Level], place_iseland, InUse order by Place)) as g
			from
			(
				select *, Place - row_number() over(partition by SectORNo, [Level] order by Place) as place_iseland
				from d
			) m
		) z
	) q
	where q.free_cnt >=3 and InUse = 0 /* тут параметр */
	order by free_cnt, SectorNo, [Level], Place
	for xml path(''))
	
	, 1, 1, ''
)