Some compilers don't like big stack frames. There is no need
for this to be a power of 2, so let's just shrink it a little.
diff --git a/src/core/lib/iomgr/tcp_posix.c b/src/core/lib/iomgr/tcp_posix.c
index ec21e03..974d5ae 100644
--- a/src/core/lib/iomgr/tcp_posix.c
+++ b/src/core/lib/iomgr/tcp_posix.c
@@ -284,7 +284,7 @@
 }
 
 /* returns true if done, false if pending; if returning true, *error is set */
-#define MAX_WRITE_IOVEC 1024
+#define MAX_WRITE_IOVEC 1000
 static bool tcp_flush(grpc_tcp *tcp, grpc_error **error) {
   struct msghdr msg;
   struct iovec iov[MAX_WRITE_IOVEC];