Document the current default stack sizes on different systems

The default stack sizes varies between operating systems and between
different system libc libraries from 128kB (Alpine Linux with MUSL) to
8M (Linux with glibc).  Document the different values used to justify
the value of THREAD_MINSTACKSIZE (currently set to 1MB).

diff --git a/lib/isc/thread_p.h b/lib/isc/thread_p.h
index 0fd02a9684ac0724fd2afa82774e75ddf57c13fc..b31e6c30387998a6215dbbfa2322e1fe83d863e4 100644 (file)
--- a/lib/isc/thread_p.h
+++ b/lib/isc/thread_p.h
@@ -17,6 +17,14 @@
 
 /*! \file */
 
+/*
+ * The current default stack sizes are as follows:
+ * - Linux glibc: 8MB
+ * - Linux musl: 128kB
+ * - FreeBSD: 2MB
+ * - OpenBSD: 512kB
+ * - NetBSD: 4MB
+ */
 #ifndef THREAD_MINSTACKSIZE
 #define THREAD_MINSTACKSIZE (1U * 1024 * 1024)
 #endif /* ifndef THREAD_MINSTACKSIZE */