SI_MAXSZ

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
  1. auto SI_MAXSZ;
  2. auto SI_MAXSZ;
    version(!linux && !OSX && !FreeBSD && solaris)
    extern (C) const
    static if(!(size_t.sizeof == 8))
    auto SI_MAXSZ = 128;

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