[F.Rq.] Some way to configure the size of the stack

[YoshiRulz]

Per discussions at #96347 (there is no official documentation†), the size of the default/global stack is fixed and differs between OSes. ASP.NET devs can use the stackSize setting (only with IIS?) to configure it. I would like to do the same with a CLI or desktop app. A new API or an environment variable would also be acceptable for me. I would use this to decrease the size in order to root out stealthy bugs, but I can also see it being used to increase the size for some non-ASP.NET server or other high-perf use case.

See also:

• Previous requests #11634 and #12042, which were closed as resolved, but OP in #96347 says the new flag was never exposed for public use.
• #30034 was requesting a new API to get the currently applicable stack size at runtime. Closed as stale.
• #8861 and #33622 inquiring as to why the stack is a different size on different OSes.

† There seemed to be no official documentation for the stack in modern .NET, and info for .NET Framework and Mono was all over the place, so I've collected everything I've found here.

[janvorli]

On Unix, you can set the default stack size this way:

• Using the ulimit -s shell command. That sets it for the main thread and on glibc based distros for secondary threads too. On MUSL based distros like Alpine, the DOTNET_DefaultStackSize needs to be used for the secondary threads.

On all OSes, but only for secondary threads, since the main thread stack size is set by the OS when launching the application and the runtime cannot influence it.

• Using the DOTNET_DefaultStackSize env variable
• Using DEFAULT_STACK_SIZE property passed to coreclr_initialize in case you have your own custom .NET host

On Windows, you can also modify the stack size set in the host executable (if you build your app, you end up having YourApp.exe and YourApp.dll, the .exe is the host)

• To set the stack size to e.g. 4MB: editbin.exe YourApp.exe /STACK:0x400000

You can also specify the thread stack size when creating new threads in your code in the constructor of the thread (public Thread (System.Threading.ThreadStart start, int maxStackSize)). However, that doesn't work for threadpool threads.

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[janvorli]

@YoshiRulz is this sufficient for you or would you like something additional?

[YoshiRulz]

My team develops on and builds for Windows and Linux, so I think we could use a combination of those 2 workarounds, but it still seems odd that there's no way to change the stack size for the main thread.

edit: I maintain that a compile-time EDITBIN invocation and a runtime ulimit invocation are both workarounds. For one, I imagine they can't be used on Android. BASH on macOS might have ulimit, not sure.

[janvorli]

it still seems odd that there's no way to change the stack size for the main thread.

@YoshiRulz there are ways to change it for the main thread both on Windows and Linux that I've mentioned in my previous comment:

• Using the ulimit -s shell command on Linux
• Modify the stack size set in the host executable on Windows using the editbin.exe.

[janvorli]

@YoshiRulz what's wrong with these ways? The default stack size for the main thread is something only the operating system can set, because it needs to be set before the process is launched and the application itself doesn't have any way to control it.

[YoshiRulz]

As per my edit above, they're not cross-platform, and one is compile-time and one is runtime.

If the runtime can't change its own stack size, perhaps it could spawn a new thread with the stack size specified in the assembly metadata (for example) and begin execution of the main method on that thread?