use the ulimit command, rtfm ulimit
When i start WIneX 3.3 i get this error.
Your system requires the use of pthreads but the maximum system allowed stack size of 2052 kB may be too small for some games.
What can i do to increase the stack size ?
use the ulimit command, rtfm ulimit
Before you spout off RTFM, maybe you should do your homework first. Check out Debian Bug #204691. Apparently Debian has the limit on the stack size set at a hard limit of 2MB. Apparently, you can patch libc6 and increase this to 8MB quite easily. The drawback is that apparently, this doesn't work on all x86 platforms, and requires some tricky packaging work to split up libc6 into 386 and 686 packages. Read the bug report for more details, including the patch.
I've also read from transgaming.com that this issue will not affect game performance, that you could just ignore the error. . .
I've been using winex 3.1 fine and always get that error. . .

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