Classic ASP IIS 6 Response buffer limit exceeded - asp.net

Question

I have a Classic ASP application which allows users to download excel documents provided by a 3rd party vendor. Below is sample code. If the document size is greater than 4mb, I get an error "Response buffer limit exceeded".
I did some research and tried different things. Only increasing the buffer limit in IIS resolved my issue. But my systems team is reluctant to make this change on production.
Is there an alternate solution? Is there a solution available in ASP.Net?
set objDoc = Server.createobject("Some.Object")
objDoc.DocId doc_id
bin_obj = objDoc.Binary
set objDoc = Nothing
Response.buffer = TRUE
Response.ContentType = "application/msexcel"
Response.AddHeader "Cache-Control", "public"
Response.AddHeader "Pragma", "public"
Response.AddHeader "Content-Disposition", "attachment;filename=test.xls"
Response.BinaryWrite bin_obj
Response.Flush
Response.End

Answer 1

You need push content part by part, ex. by 1Mb per block. If your COM object ("Some.Object") dosn't allow read by block, you can make it using ADODB.Stream object with method stream.Read(count).
UPDATE:
Option Explicit
Dim streamS, streamB
Set streamS = Server.CreateObject("ADODB.Stream")
streamS.Type = 1 'Binary stream
streamS.Open
streamS.LoadFromFile Server.MapPath("/Nissan_Qashqai_IDTR.rar")
Set streamB = Server.CreateObject("ADODB.Stream")
streamB.Type = 1
streamB.Open
Dim blockSize
blockSize = 1024 ' block size is 1 KB
Response.AddHeader "Content-Disposition", "attachment;filename=MyTestBinryFile.bin"
Response.AddHeader "Content-Length", streamS.Size
Response.ContentType = "application/octet-stream"
Dim i
For i = 0 To streamS.Size - 1 Step blockSize
streamB.Position = 0
streamS.CopyTo streamB, blockSize
streamB.Position = 0
Response.BinaryWrite(streamB.Read)
Response.Flush
Next
streamS.Close
Set streamS = Nothing
streamB.Close
Set streamB = Nothing
Response.Flush