tag the fifo/dev_fd file descriptor

patches/subst.c

@@ -0,0 +1,32 @@
+diff --git a/subst.c b/subst.c
+index d9feabc..14d7516 100644
+--- a/subst.c
++++ b/subst.c
+@@ -6505,6 +6505,7 @@ process_substitute (string, open_for_read_in_child)
+
+   pathname = make_dev_fd_filename (parent_pipe_fd);
+ #endif /* HAVE_DEV_FD */
++  
+
+   if (pathname == 0)
+     {
+@@ -6648,6 +6649,10 @@ process_substitute (string, open_for_read_in_child)
+
+       exit (127);
+     }
++#ifdef __MVS__
++  __chgfdccsid(fd, 819);
++#endif
++
+   if (open_for_read_in_child)
+     {
+       if (sh_unset_nodelay_mode (fd) < 0)
+@@ -6659,7 +6664,7 @@ process_substitute (string, open_for_read_in_child)
+ #else /* HAVE_DEV_FD */
+   fd = child_pipe_fd;
+ #endif /* HAVE_DEV_FD */
+-
++  
+   /* Discard  buffered stdio output before replacing the underlying file
+      descriptor. */
+   if (open_for_read_in_child == 0)