zkStdlib.h is a portable wrapper for the Standard C header <stdlib.h>. It is part of the libzk library because there are parts of the Zero Knowledge code base that assume it contains functionality beyond that provided by Standard C, namely POSIX or platform-specific features.

zkTime.h - Supported Macros from <time.h>
Macro Description
CLOCKS_PER_SEC A number used to convert the value returned by the clock() function into seconds. It should not be assumed that CLOCKS_PER_SEC is a compile-time constant.

zkTime.h - Supported Types from <time.h>
Type Description
clock_t An arithmetic type used to hold the return value of the time() function. The value represents elapsed processor time.
time_t

An arithmetic type used to hold the return value of the time() function. The value represents calendar time.

Important: do not assume anything about the encoding of this type; the encoding is implementation-defined under Standard C. In particular, do not assume that a time_t holds the number of seconds elapsed since January 1, 1970.

tm_sec, a struct with members:  
int tm_sec
seconds [0,61]
int tm_min
minutes [0,59]
int tm_hour
hour [0,23]
int tm_mday
day of month [1,31]
int tm_mon
month of year [0,11]
int tm_year
years since 1900
int tm_wday
day of week [0,6] (Sunday = 0)
int tm_yday
day of year [0,365]
int tm_isdst
daylight savings flag

zkTime.h - Supported Functions from <time.h>
asctime
clock
ctime
difftime
gmtime
localtime
mktime
strftime
time