diff --git a/src/ca/cac.h b/src/ca/cac.h
index 8ef88c381..9dfcf2f96 100644
--- a/src/ca/cac.h
+++ b/src/ca/cac.h
@@ -109,6 +109,14 @@ public:
         epicsGuard < cacMutex > &, nciu & chan ) = 0;
 };
 
+class cacMessageProcessingMinder {
+public:
+    cacMessageProcessingMinder ( class cac & );
+    ~cacMessageProcessingMinder ();
+private:
+    class cac & cacRef;
+};
+
 class cac : private cacRecycle, private cacDisconnectChannelPrivate,
     private callbackForMultiplyDefinedPV
 {
@@ -193,8 +201,6 @@ public:
     void initiateAbortShutdown ( tcpiiu & );
     void disconnectNotify ( tcpiiu & );
     void uninstallIIU ( tcpiiu & ); 
-    void messageArrivalNotify ();
-    void messageProcessingCompleteNotify ();
 
 private:
     localHostName hostNameCache;
@@ -340,10 +346,26 @@ private:
                     const char *pCtx, unsigned status );
     static const pExcepProtoStubTCP tcpExcepJumpTableCAC [];
 
+    void messageArrivalNotify ();
+    void messageProcessingCompleteNotify ();
+
 	cac ( const cac & );
 	cac & operator = ( const cac & );
+
+    friend class cacMessageProcessingMinder;
 };
 
+inline cacMessageProcessingMinder::cacMessageProcessingMinder ( cac & cacIn ) :
+    cacRef ( cacIn )
+{
+    cacIn.messageArrivalNotify ();
+}
+
+inline cacMessageProcessingMinder::~cacMessageProcessingMinder ()
+{
+    cacRef.messageProcessingCompleteNotify ();
+}
+
 inline const char * cac::userNamePointer () const
 {
     return this->pUserName;
diff --git a/src/ca/tcpiiu.cpp b/src/ca/tcpiiu.cpp
index 2e751ca9d..85fca9ef6 100644
--- a/src/ca/tcpiiu.cpp
+++ b/src/ca/tcpiiu.cpp
@@ -323,49 +323,49 @@ void tcpRecvThread::run ()
             // - it take also the callback lock
             this->iiu.recvDog.messageArrivalNotify ( currentTime ); 
 
-            this->iiu.cacRef.messageArrivalNotify ();
+            cacMessageProcessingMinder msgProcMinder ( this->iiu.cacRef );
+            {
+                // only one recv thread at a time may call callbacks
+                // - pendEvent() blocks until threads waiting for
+                // this lock get a chance to run
+                epicsGuard < callbackMutex > guard ( this->cbMutex );
 
-            // only one recv thread at a time may call callbacks
-            // - pendEvent() blocks until threads waiting for
-            // this lock get a chance to run
-            epicsGuard < callbackMutex > guard ( this->cbMutex );
-
-            // force the receive watchdog to be reset every 5 frames
-            unsigned contiguousFrameCount = 0;
-            while ( nBytesIn ) {
-                if ( nBytesIn == pComBuf->capacityBytes () ) {
-                    if ( this->iiu.contigRecvMsgCount >= 
-                        contiguousMsgCountWhichTriggersFlowControl ) {
-                        this->iiu.busyStateDetected = true;
+                // force the receive watchdog to be reset every 5 frames
+                unsigned contiguousFrameCount = 0;
+                while ( nBytesIn ) {
+                    if ( nBytesIn == pComBuf->capacityBytes () ) {
+                        if ( this->iiu.contigRecvMsgCount >= 
+                            contiguousMsgCountWhichTriggersFlowControl ) {
+                            this->iiu.busyStateDetected = true;
+                        }
+                        else { 
+                            this->iiu.contigRecvMsgCount++;
+                        }
                     }
-                    else { 
-                        this->iiu.contigRecvMsgCount++;
+                    else {
+                        this->iiu.contigRecvMsgCount = 0u;
+                        this->iiu.busyStateDetected = false;
+                    }         
+                    this->iiu.unacknowledgedSendBytes = 0u;
+
+                    this->iiu.recvQue.pushLastComBufReceived ( *pComBuf );
+                    pComBuf = new ( this->iiu.comBufMemMgr ) comBuf;
+
+                    // execute receive labor
+                    bool protocolOK = this->iiu.processIncoming ( currentTime, guard );
+                    if ( ! protocolOK ) {
+                        this->iiu.cacRef.initiateAbortShutdown ( this->iiu );
+                        break;
                     }
+
+                    if ( ! this->iiu.bytesArePendingInOS ()
+                        || ++contiguousFrameCount > 5 ) {
+                        break;
+                    }
+
+                    nBytesIn = pComBuf->fillFromWire ( this->iiu );
                 }
-                else {
-                    this->iiu.contigRecvMsgCount = 0u;
-                    this->iiu.busyStateDetected = false;
-                }         
-                this->iiu.unacknowledgedSendBytes = 0u;
-
-                this->iiu.recvQue.pushLastComBufReceived ( *pComBuf );
-                pComBuf = new ( this->iiu.comBufMemMgr ) comBuf;
-
-                // execute receive labor
-                bool protocolOK = this->iiu.processIncoming ( currentTime, guard );
-                if ( ! protocolOK ) {
-                    this->iiu.cacRef.initiateAbortShutdown ( this->iiu );
-                    break;
-                }
-
-                if ( ! this->iiu.bytesArePendingInOS ()
-                    || ++contiguousFrameCount > 5 ) {
-                    break;
-                }
-
-                nBytesIn = pComBuf->fillFromWire ( this->iiu );
             }
-            this->iiu.cacRef.messageProcessingCompleteNotify ();
         }
 
         if ( pComBuf ) {
@@ -373,8 +373,22 @@ void tcpRecvThread::run ()
             this->iiu.comBufMemMgr.release ( pComBuf );
         }
     }
+    catch ( std::bad_alloc & ) {
+        errlogPrintf ( 
+            "CA client library tcp receive thread "
+            "terminating due to no space in pool "
+            "C++ exception\n" );
+    }
+    catch ( std::exception & except ) {
+        errlogPrintf ( 
+            "CA client library tcp receive thread "
+            "terminating due to C++ exception \"%s\"\n", 
+            except.what () );
+    }
     catch ( ... ) {
-        errlogPrintf ( "cac tcp receive thread terminating due to a c++ exception\n" );
+        errlogPrintf ( 
+            "CA client library tcp receive thread "
+            "terminating due to a C++ exception\n" );
     }
 
     // Although this is redundant in certain situations it is
diff --git a/src/ca/udpiiu.cpp b/src/ca/udpiiu.cpp
index 8775ad3f8..5ae3102f3 100644
--- a/src/ca/udpiiu.cpp
+++ b/src/ca/udpiiu.cpp
@@ -244,8 +244,7 @@ void udpiiu::recvMsg ( callbackMutex & cbMutex )
         this->recvBuf, sizeof ( this->recvBuf ), 0,
         & src.sa, & src_size );
 
-    this->cacRef.messageArrivalNotify ();
-
+    cacMessageProcessingMinder msgProcMinder ( this->cacRef );
     {
         epicsGuard < callbackMutex > guard ( cbMutex );
 
@@ -286,8 +285,6 @@ void udpiiu::recvMsg ( callbackMutex & cbMutex )
                 (arrayElementCount) status, epicsTime::getCurrent() );
         }
     }
-
-    this->cacRef.messageProcessingCompleteNotify ();
 }
 
 udpRecvThread::udpRecvThread ( udpiiu & iiuIn, callbackMutex & cbMutexIn,