[PATCH 1/3] lib/core/fiber: Increase default stack size

[Cyrill Gorcunov <gorcunov@gmail.com>]

The default 64K stack size used for years become too small
for modern distors (Fedora 29 and etc) where third party libraries
(such as ncurses) started to use 64K for own buffers and we get
SIGSGV early without reaching interactive console phase.

Thus we increase default size up to 512K which should fit
for common case. Later we will make this value configurable
to address arbitrary stack sizes without a need to rebuild
the whole code.

Note the values are switched to 4K page granularity for sake
of future modifications -- we gonna manipulate pages to
relax rss usage if OS allows.

Closes #3418
---
 src/lib/core/fiber.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/lib/core/fiber.c b/src/lib/core/fiber.c
index abd6c6b11..f16ac873f 100644
--- a/src/lib/core/fiber.c
+++ b/src/lib/core/fiber.c
@@ -93,9 +93,9 @@ static int stack_direction;
 
 enum {
 	/* The minimum allowable fiber stack size in bytes */
-	FIBER_STACK_SIZE_MINIMAL = 16384,
+	FIBER_STACK_SIZE_MINIMAL = 4 << 12,
 	/* Default fiber stack size in bytes */
-	FIBER_STACK_SIZE_DEFAULT = 65536
+	FIBER_STACK_SIZE_DEFAULT = 128 << 12
 };
 
 /** Default fiber attributes */
-- 
2.20.1