Use symbolic constant

src/core/channel/client_channel.c

@@ -410,7 +410,7 @@ static void init_channel_elem(grpc_channel_element *elem,
                               grpc_mdctx *metadata_context, int is_first,
                               int is_last) {
   channel_data *chand = elem->channel_data;
-  char temp[16];
+  char temp[GPR_LTOA_MIN_BUFSIZE];
 
   GPR_ASSERT(!is_first);
   GPR_ASSERT(is_last);

src/core/surface/call.c

@@ -822,7 +822,7 @@ grpc_call_error grpc_call_start_write_status(grpc_call *call,
   /* always send status */
   {
     grpc_mdelem *md;
-    char buffer[32];
+    char buffer[GPR_LTOA_MIN_BUFSIZE];
     gpr_ltoa(status, buffer);
     md =
         grpc_mdelem_from_strings(call->metadata_context, "grpc-status", buffer);

src/core/transport/chttp2_transport.c

@@ -1002,7 +1002,7 @@ static void cancel_stream_inner(transport *t, stream *s, gpr_uint32 id,
                                 grpc_chttp2_error_code error_code,
                                 int send_rst) {
   int had_outgoing;
-  char buffer[32];
+  char buffer[GPR_LTOA_MIN_BUFSIZE];
 
   if (s) {
     /* clear out any unreported input & output: nobody cares anymore */