#
# 	compile on Plan9
#
mk

#
#	compile on UNIX (plan9port is required)
#
9c -DUNIX 9xa.c && 9l -o 9xa 9xa.o


#
#	Note on ARG_MAX (merely my memo. ARG_MAX is not used)
#

# Mac/OSX
/usr/include/sys/syslimits.h
#define	ARG_MAX		   (256 * 1024)	/* max bytes for an exec function */


# 9vx
/usr/local/9vx-0.12/sys/include/ape/sys/limits.h:
define	ARG_MAX		16384

# Plan9
we can know the upper limit from TSTKSIZ (thanks Charles Forsyth)
cpu% cd /sys/src/9
cpu% grep TSTKSIZ */*.h */*/*.h
alphapc/mem.h:#define	USTKTOP	(TSTKTOP-TSTKSIZ*BY2PG)	/* byte just beyond user stack */
alphapc/mem.h:#define	TSTKSIZ 100
bitsy/mem.h:#define	TSTKSIZ	 	100
kw/mem.h:#define	TSTKSIZ	 	256
mtx/mem.h:#define	USTKTOP	(TSTKTOP-TSTKSIZ*BY2PG)	/* byte just beyond user stack */
mtx/mem.h:#define	TSTKSIZ 100
omap/mem.h:#define	TSTKSIZ	 	256
pc/mem.h:#define	TSTKSIZ 	100			/* pages in new stack; limits exec args */
ppc/mem.h:#define	USTKTOP		(TSTKTOP-TSTKSIZ*BY2PG)	/* byte just beyond user stack */
ppc/mem.h:#define	TSTKSIZ		100
grep: can't open */*/*.h: '*' file does not exist
cpu% 
the unit of TSTKSIZ is page(4KB)