Many small edits.
diff --git a/src/libthread/channel.c b/src/libthread/channel.c
index 4dc51fc..903889a 100644
--- a/src/libthread/channel.c
+++ b/src/libthread/channel.c
@@ -249,6 +249,7 @@
 	Channel *c;
 	_Thread *t;
 
+	needstack(512);
 	for(i=0; a[i].op != CHANEND && a[i].op != CHANNOBLK; i++)
 		;
 	n = i;