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Description of the IRPStackSize parameter in Windows 2000, in Windows XP, and in Windows Server 2003

Article ID: 285089 - View products that this article applies to.

This article was previously published under Q285089

INTRODUCTION

This article describes the functionality of the IRPStackSize parameter in Microsoft Windows 2000 Server, in Microsoft Windows XP, and in Microsoft Windows Server 2003.

Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:

322756

(http://support.microsoft.com/kb/322756/ )

How to back up and restore the registry in Windows

The IRPStackSize parameter specifies the number of stack locations in I/O request packets (IRPs) that are used by Windows 2000 Server, by Windows Server 2003, and by Windows XP. You may have to increase this number for certain transports, for media access control (MAC) drivers, or for file system drivers. Each stack uses 36 bytes of memory for each receive buffer. This value is set in the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

The default value of the IRPStackSize parameter is 15. The range is from 11 (0xb hexadecimal) through 50 (0x32 hexadecimal).

If the subkey is not present, you can use Registry Editor to add the subkey. To do this, follow these steps:

Click Start, click Run, type regedit, and then click OK.
Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters
Click Edit, point to New, and then click DWORD Value.
Type IRPStackSize, and then press ENTER to name the value.

Note Type IRPStackSize exactly as it is displayed. The value name is case sensitive.
Click Edit, and then click Modify.
In the Data Value box, type the value that is appropriate for the network, and then click OK.

If the problem persists after you complete this procedure, increase the value of IRPStackSize even more.

Note On some computers, values from 33 through 38 can cause problems. For information about a hotfix that addresses these problems, click the following article number to visit the article in the Microsoft Knowledge Base:

924749

(http://support.microsoft.com/kb/924749/ )

Event ID 2021 is logged even though lots of non-paged pool memory is available in Windows Server 2003