I'm in the same boat as far as knowing what IRP stacks are for, but...

Some of what I've gleaned (is that a word?).


IRPstackSize REG_DWORD 1 to 12
Default: 4
Specifies the number of stack locations in I/O Request Packets (IRPs) used by the server. It may be necessary to increase this number for certain transports, MAC drivers, or local file system drivers. Each increment costs 36 bytes of memory per work item (that is, #work items * 36 bytes = total memory cost).


Some relationship to TCP/IP. Windows sockets. AFD Registry paramaters. And who know what else.


Programs that seem to affect/be affected by IRPstackSize.
QuotaAdvisor. ARCServe. Lanman Server. File and Print Services for NetWare. Norton AntiVirus for Windows or IBM AntiVirus 3.01N. WinVNC.


<http://www.windows2000faq.com/Articles/Index.cfm?ArticleID=23314>
Windows XP, Windows 2000, and Windows NT all have an IRPStackSize value that controls how much physical storage space and RAM are available to new applications, and some new software installs incorrectly set this value. This value ranges from 11 to 20 for XP and from 11 to 15 for Win2K and NT. If you set this value to less than 11, you'll receive an error message indicating that the system doesn't have enough server storage. As a result, clients won't be able to access network shares and Event ID 2011 will appear in the System log.


<http://service1.symantec.com/SUPPORT/tsgeninfo.nsf/7e7f15291a25d938882567e50048a048/c5f235e31e2baaa588256bc2007088ff?OpenDocument&sone=_tasks.html&stg=∏;=&ver=&base=&next=&src=ent&pcode=&dtype=corp&svy=&prev=>
Changing the IRPStackSize is sometimes necessary to fix problems or for troubleshooting a problem that occur when it is set too low. In most cases, you should not do this unless it is recommend by another Symantec knowledge base document or a Symantec technician.


The server preallocates I/O request packets to be the size specified by the IRPSTACKSIZE parameter in the configuration information. The value of this parameter must be as large as the size required by any transport or file system in the network.


<http://support.precisesrm.com/scripts/support.cfg/php.exe/enduser/std_adp.php?p_faqid=364>
On machines with a large amount of file activity, you might get "Not Enough Server Storage is available to process this command" error after installing StorageCentral, and users cannot connect to the server. This occurs because the server's current configuration for I/O Request Packets (IRPs) is too low. The problem occurs on Windows NT 4.0 and Windows 2000. You can correct the problem by increasing the registry value and restarting the server.


<http://www.windows2000faq.com/Articles/Index.cfm?ArticleID=14571>


<http://search.microsoft.com/default.asp?IntCat=0&IntCat=1&IntCat=2&IntCat=3&IntCat=4&IntCat=5&IntCat=6&IntCat=7&IntCat=8&IntCat=9&Boolean=ALL&Nq=NEW&qu=irpstacksize&btnSearch=GO&ig=1&ig=2&ig=3&ig=4&ig=5&ig=6&ig=7&ig=8&ig=9&ig=10&siteid=us>
A bunch of MS articles on irpstacksize.


<http://www.jsifaq.com/_vti_script/reghackSrch.htm0.idq>
Search for irpstacksize