diff -ur icu.org/source/common/uposixdefs.h icu/source/common/uposixdefs.h
--- icu.org/source/common/uposixdefs.h	2017-03-09 03:12:45.000000000 +0100
+++ icu/source/common/uposixdefs.h	2017-04-21 22:23:11.857926971 +0200
@@ -54,7 +54,7 @@
  *
  * z/OS needs this definition for timeval and to get usleep.
  */
-#if !defined(_XOPEN_SOURCE_EXTENDED) && defined(__TOS_MVS__)
+#if !defined(_XOPEN_SOURCE_EXTENDED) && (defined(__TOS_MVS__) || defined(__IBMC__) || defined(__IBMCPP__))
 #   define _XOPEN_SOURCE_EXTENDED 1
 #endif
 
