diff --git a/src/ca/tcpiiu.cpp b/src/ca/tcpiiu.cpp
index 51ac538bd..b6617acd0 100644
--- a/src/ca/tcpiiu.cpp
+++ b/src/ca/tcpiiu.cpp
@@ -126,13 +126,16 @@ void tcpiiu::connect ()
     }
 }
 
-/*
- *  cacSendThreadTCP ()
- */
+//
+//  cacSendThreadTCP ()
+//
+// care is taken to not hold the lock while sending a message
+//
 extern "C" void cacSendThreadTCP ( void *pParam )
 {
     tcpiiu *piiu = ( tcpiiu * ) pParam;
     claimMsgCache cache ( CA_V44 ( CA_PROTOCOL_VERSION, piiu->minorProtocolVersionNumber ) );
+    bool laborNeeded;
 
     while ( true ) {
 
@@ -142,32 +145,61 @@ extern "C" void cacSendThreadTCP ( void *pParam )
             break;
         }
 
-        if ( piiu->pClaimsPendingIIU->channelCount () > 0u ) {
-            piiu->pClaimsPendingIIU->sendPendingClaims ( *piiu,
+        piiu->lock ();
+        laborNeeded = piiu->claimsPending;
+        piiu->claimsPending = false;
+        piiu->unlock ();
+        if ( laborNeeded ) {
+            piiu->sendPendingClaims ( 
                 CA_V42 ( CA_PROTOCOL_VERSION, piiu->minorProtocolVersionNumber ), cache );
             piiu->flushPending = true;
         }
 
-        if ( piiu->busyStateDetected != piiu->flowControlActive ) {
+        piiu->lock ();
+        laborNeeded = piiu->busyStateDetected != piiu->flowControlActive;
+        piiu->unlock ();            
+        if ( laborNeeded ) {
             if ( piiu->flowControlActive ) {
-                piiu->enableFlowControlMsg ();
+                piiu->comQueSend::disableFlowControlRequest ();
+                piiu->flowControlActive = false;
+#               if defined ( DEBUG ) || 1
+                    printf ( "fc off\n" );
+#               endif
             }
             else {
-                piiu->disableFlowControlMsg ();
+                piiu->comQueSend::enableFlowControlRequest ();
+                piiu->flowControlActive = true;
+#               if defined ( DEBUG ) || 1
+                    printf ( "fc on\n" );
+#               endif
             }
             piiu->flushPending = true;
         }
 
-        if ( piiu->echoRequestPending ) {
-            piiu->echoRequestMsg ();
+        piiu->lock ();
+        laborNeeded = piiu->echoRequestPending;
+        piiu->echoRequestPending = false;
+        piiu->unlock ();
+
+        if ( laborNeeded ) {
+            if ( CA_V43 ( CA_PROTOCOL_VERSION, piiu->minorProtocolVersionNumber ) ) {
+                piiu->comQueSend::echoRequest ();
+            }
+            else {
+                piiu->comQueSend::noopRequest ();
+            }
             piiu->flushPending = true;
         }
 
-        if ( piiu->flushPending ) {
+        piiu->lock ();
+        laborNeeded = piiu->flushPending;
+        piiu->flushPending = false;
+        piiu->unlock ();
+
+        if ( laborNeeded ) {
             if ( ! piiu->flushToWire () ) {
                 break;
             }
-            piiu->flushPending = false;
         }
     }
 
@@ -269,6 +301,7 @@ unsigned tcpiiu::recvBytes ( void *pBuf, unsigned nBytesInBuf )
     assert ( static_cast <unsigned> ( status ) <= nBytesInBuf );
     totalBytes = static_cast <unsigned> ( status );
 
+    this->lock ();
     if ( nBytesInBuf == totalBytes ) {
         if ( this->contigRecvMsgCount >= contiguousMsgCountWhichTriggersFlowControl ) {
             this->busyStateDetected = true;
@@ -281,6 +314,7 @@ unsigned tcpiiu::recvBytes ( void *pBuf, unsigned nBytesInBuf )
         this->contigRecvMsgCount = 0u;
         this->busyStateDetected = false;
     }
+    this->unlock ();
     
     this->messageArrivalNotify (); // reschedule connection activity watchdog
 
@@ -349,7 +383,8 @@ tcpiiu::tcpiiu ( cac &cac, const osiSockAddr &addrIn,
     flowControlActive ( false ),
     recvMessagePending ( false ),
     flushPending ( false ),
-    msgHeaderAvailable ( false )
+    msgHeaderAvailable ( false ),
+    claimsPending ( false )
 {
     SOCKET newSocket;
     int status;
@@ -363,10 +398,6 @@ tcpiiu::tcpiiu ( cac &cac, const osiSockAddr &addrIn,
         return;
     }
 
-    //
-    // apparently this is nolonger necessary with modern IP kernels
-    //
-#if 0
     flag = TRUE;
     status = setsockopt ( newSocket, IPPROTO_TCP, TCP_NODELAY,
                 (char *)&flag, sizeof(flag) );
@@ -374,7 +405,7 @@ tcpiiu::tcpiiu ( cac &cac, const osiSockAddr &addrIn,
         ca_printf ("CAC: problems setting socket option TCP_NODELAY = \"%s\"\n",
             SOCKERRSTR (SOCKERRNO));
     }
-#endif
+
     flag = TRUE;
     status = setsockopt ( newSocket , SOL_SOCKET, SO_KEEPALIVE,
                 (char *)&flag, sizeof (flag) );
@@ -438,21 +469,11 @@ tcpiiu::tcpiiu ( cac &cac, const osiSockAddr &addrIn,
         return;
     }
 
-    this->pClaimsPendingIIU = new claimsPendingIIU ( *this );
-    if ( ! this->pClaimsPendingIIU ) {
-        ca_printf ("CA: unable to create claimsPendingIIU object\n");
-        semBinaryDestroy (this->sendThreadExitSignal);
-        socket_close ( newSocket );
-        this->fullyConstructedFlag = false;
-        return;
-    }
-
     this->sendThreadFlushSignal = semBinaryCreate ( semEmpty );
     if ( ! this->sendThreadFlushSignal ) {
         ca_printf ("CA: unable to create sendThreadFlushSignal object\n");
         semBinaryDestroy (this->sendThreadExitSignal);
         socket_close ( newSocket );
-        delete this->pClaimsPendingIIU;
         this->fullyConstructedFlag = false;
         return;
     }
@@ -463,7 +484,6 @@ tcpiiu::tcpiiu ( cac &cac, const osiSockAddr &addrIn,
         semBinaryDestroy (this->sendThreadExitSignal);
         semBinaryDestroy (this->sendThreadFlushSignal);
         socket_close ( newSocket );
-        delete this->pClaimsPendingIIU;
         this->fullyConstructedFlag = false;
         return;
     }
@@ -490,7 +510,6 @@ tcpiiu::tcpiiu ( cac &cac, const osiSockAddr &addrIn,
             semBinaryDestroy (this->recvThreadExitSignal);
             semBinaryDestroy (this->sendThreadExitSignal);
             socket_close ( newSocket );
-            delete this->pClaimsPendingIIU;
             semBinaryDestroy (this->sendThreadFlushSignal);
             semBinaryDestroy (this->recvThreadRingBufferSpaceAvailableSignal);
             this->fullyConstructedFlag = false;
@@ -556,6 +575,8 @@ tcpiiu::~tcpiiu ()
 
     this->fullyConstructedFlag = false;
 
+    this->clientCtx ().removeIIU ( *this );
+
     if ( this->channelCount () ) {
         char hostNameTmp[64];
         this->ipToA.hostName ( hostNameTmp, sizeof ( hostNameTmp ) );
@@ -564,11 +585,6 @@ tcpiiu::~tcpiiu ()
 
     this->disconnectAllChan ();
 
-    if ( this->pClaimsPendingIIU ) {
-        this->pClaimsPendingIIU->disconnectAllChan ();
-        delete this->pClaimsPendingIIU;
-    }
-
     this->cleanShutdown ();
 
     // wait for send and recv threads to exit
@@ -580,8 +596,6 @@ tcpiiu::~tcpiiu ()
     semBinaryDestroy ( this->sendThreadFlushSignal );
     semBinaryDestroy ( this->recvThreadRingBufferSpaceAvailableSignal );
 
-    this->clientCtx ().removeIIU ( *this );
-
     /*
      * free message body cache
      */
@@ -643,9 +657,6 @@ void tcpiiu::show ( unsigned level ) const
         printf ("\treceive message pending bool = %u\n", this->recvMessagePending );
         printf ("\tflush pending bool = %u\n", this->flushPending );
         printf ("\treceive message header available bool = %u\n", this->msgHeaderAvailable );
-        if ( this->pClaimsPendingIIU ) {
-            this->pClaimsPendingIIU->show ( level - 3u );
-        }
         this->bhe.show ( level - 3u );
     }
     this->unlock ();
@@ -653,49 +664,12 @@ void tcpiiu::show ( unsigned level ) const
 
 void tcpiiu::echoRequest ()
 {
+    this->lock ();
     this->echoRequestPending = true;
+    this->unlock ();
     this->flush ();
 }
 
-/*
- * tcpiiu::echoRequestMsg ()
- */
-void tcpiiu::echoRequestMsg ()
-{
-    if ( CA_V43 ( CA_PROTOCOL_VERSION, this->minorProtocolVersionNumber ) ) {
-        this->comQueSend::echoRequest ();
-    }
-    else {
-        this->comQueSend::noopRequest ();
-    }
-
-    this->echoRequestPending = false;
-}
-
-/*
- *  tcpiiu::enableFlowControlMsg ()
- */
-void tcpiiu::enableFlowControlMsg ()
-{
-    this->comQueSend::enableFlowControlRequest ();
-    this->flowControlActive = true;
-#   if defined ( DEBUG ) || 1
-    printf( "fc on\n" );
-#   endif
-}
-
-/*
- * tcpiiu::disableFlowControlMsg ()
- */
-void tcpiiu::disableFlowControlMsg ()
-{
-    this->comQueSend::disableFlowControlRequest ();
-    this->flowControlActive = false;
-#   if defined ( DEBUG ) || 1
-        printf ( "fc off\n" );
-#   endif
-}
-
 /*
  * tcpiiu::hostNameSetMsg ()
  */
@@ -914,7 +888,7 @@ void tcpiiu::accessRightsRespAction ()
 
 void tcpiiu::claimCIURespAction ()
 {
-    this->clientCtx ().connectChannel ( this->curMsg.m_cid, *this, 
+    this->clientCtx ().connectChannel ( this->ca_v44_ok (), this->curMsg.m_cid, 
         this->curMsg.m_dataType, this->curMsg.m_count, this->curMsg.m_available );
 }
 
@@ -1108,8 +1082,11 @@ void tcpiiu::lastChannelDetachNotify ()
 
 void tcpiiu::installChannelPendingClaim ( nciu &chan )
 {
-    chan.attachChanToIIU ( *this->pClaimsPendingIIU );
-    // wake up send thread which sends claim message
+    chan.attachChanToIIU ( *this );
+    this->lock ();
+    this->claimsPending = true;
+    this->unlock ();
+    // wake up send thread which ultimately sends the claim message
     semBinaryGive ( this->sendThreadFlushSignal );
 }
 
@@ -1121,7 +1098,9 @@ void tcpiiu::installChannelPendingClaim ( nciu &chan )
 bool tcpiiu::flushToWirePermit ()
 {
     if ( this->clientCtx ().currentThreadIsRecvProcessThread () ) {
+        this->lock ();
         this->flushPending = true;
+        this->unlock ();
         semBinaryGive ( this->sendThreadFlushSignal );
         return false;
     }
@@ -1130,4 +1109,3 @@ bool tcpiiu::flushToWirePermit ()
     }
 }
 
-