Yes, that helps a lot:

 gdt 156 ~/SOFTWARE/CODA/lwp/src > ./tdb 
Main thread going to create procA
Main thread going to create procB
Main thread going to create procC 
Main thread returned from creating procC  
procA starting ...
procA:please input a number9
procB starting ...
procB waiting on d...
procC starting ...
procC:please input a number3

procC doing a no yield signal on char d...
procB waiting via QWait 
procC yielding by waiting for char c ...

Index: tdb.c
===================================================================
RCS file: /coda-src/lwp/src/tdb.c,v
retrieving revision 4.10
diff -u -r4.10 tdb.c
--- tdb.c       3 Mar 2005 18:53:51 -0000       4.10
+++ tdb.c       25 Apr 2006 17:11:57 -0000
@@ -65,11 +65,11 @@
     LWP_Init(LWP_VERSION, LWP_NORMAL_PRIORITY+1, &mainthread);
     IOMGR_Initialize();
     printf("Main thread going to create procA\n");
-    LWP_CreateProcess(procA, 2048, LWP_NORMAL_PRIORITY, NULL, "procA", &A_pid);
+    LWP_CreateProcess(procA, 8192, LWP_NORMAL_PRIORITY, NULL, "procA", &A_pid);
     printf("Main thread going to create procB\n");
-    LWP_CreateProcess(procB, 2048, LWP_NORMAL_PRIORITY, NULL, "procB", &B_pid); 
+    LWP_CreateProcess(procB, 8192, LWP_NORMAL_PRIORITY, NULL, "procB", &B_pid); 
     printf("Main thread going to create procC \n");
-    LWP_CreateProcess(procC, 2048, LWP_NORMAL_PRIORITY, NULL, "procC", &C_pid);
+    LWP_CreateProcess(procC, 8192, LWP_NORMAL_PRIORITY, NULL, "procC", &C_pid);
     printf("Main thread returned from creating procC  \n");
     LWP_WaitProcess(&b);
     exit(0);

-- 
        Greg Troxel <gdt_at_ir.bbn.com>