diff --git a/src/ca/tcpiiu.cpp b/src/ca/tcpiiu.cpp
index db81b6a1b..9f45eefb9 100644
--- a/src/ca/tcpiiu.cpp
+++ b/src/ca/tcpiiu.cpp
@@ -94,7 +94,7 @@ void tcpSendThread::run ()
         }
     }
     catch ( ... ) {
-        this->iiu.printf ("cac: tcp send thread received an exception - disconnecting\n");
+        this->iiu.printf ("cac: tcp send thread received an unexpected exception - disconnecting\n");
         this->iiu.forcedShutdown ();
     }
 
@@ -226,120 +226,66 @@ void tcpRecvThread::start ()
 
 void tcpRecvThread::run ()
 {
-    this->iiu.pCAC()->attachToClientCtx ();
+    try {
+        this->iiu.pCAC()->attachToClientCtx ();
 
-    epicsThreadPrivateSet ( caClientCallbackThreadId, &this->iiu );
+        epicsThreadPrivateSet ( caClientCallbackThreadId, &this->iiu );
 
-    this->iiu.connect ();
+        this->iiu.connect ();
 
-    this->iiu.versionMessage ( this->iiu.priority() );
+        this->iiu.versionMessage ( this->iiu.priority() );
 
-    if ( this->iiu.state == iiu_connected ) {
-        this->iiu.sendThread.start ();
-    }
-    else {
-        this->iiu.sendThreadExitEvent.signal ();
-        this->iiu.cleanShutdown ();
-    }
-
-    comBuf * pComBuf = new ( std::nothrow ) comBuf;
-    while ( this->iiu.state == iiu_connected ) {
-        if ( ! pComBuf ) {
-            // no way to be informed when memory is available
-            epicsThreadSleep ( 0.5 );
-            pComBuf = new ( std::nothrow ) comBuf;
-            continue;
-        }
-
-        //
-        // We leave the bytes pending and fetch them after
-        // callbacks are enabled when running in the old preemptive 
-        // call back disabled mode so that asynchronous wakeup via
-        // file manager call backs works correctly. This does not 
-        // appear to impact performance.
-        //
-        unsigned nBytesIn;
-        if ( this->iiu.pCAC()->preemptiveCallbakIsEnabled() ) {
-            nBytesIn = pComBuf->fillFromWire ( this->iiu );
-            if ( nBytesIn == 0u ) {
-                break;
-            }
+        if ( this->iiu.state == iiu_connected ) {
+            this->iiu.sendThread.start ();
         }
         else {
-            char buf;
-            ::recv ( this->iiu.sock, &buf, 1, MSG_PEEK );
-            nBytesIn = 0u; // make gnu hoppy
-        }
- 
-        if ( this->iiu.state != iiu_connected ) {
-            break;
+            this->iiu.sendThreadExitEvent.signal ();
+            this->iiu.cleanShutdown ();
         }
 
-        // reschedule connection activity watchdog
-        // but dont hold the lock for fear of deadlocking 
-        // because cancel is blocking for the completion
-        // of the recvDog expire which takes the lock
-        // - it take also the callback lock
-        this->iiu.recvDog.messageArrivalNotify (); 
-
-        // 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 );
-
-        if ( ! this->iiu.pCAC()->preemptiveCallbakIsEnabled() ) {
-            nBytesIn = pComBuf->fillFromWire ( this->iiu );
-            if ( nBytesIn == 0u ) {
-                // outer loop checks to see if state is connected
-                // ( properly set by fillFromWire() )
-                break;
+        comBuf * pComBuf = new comBuf;
+        while ( this->iiu.state == iiu_connected ) {
+            if ( ! pComBuf ) {
+                pComBuf = new comBuf;
             }
-        }
 
-        // force the receive watchdog to be reset every 50 frames
-        unsigned contiguousFrameCount = 0;
-        while ( contiguousFrameCount++ < 50 ) {
-
-            if ( nBytesIn == pComBuf->capacityBytes () ) {
-                if ( this->iiu.contigRecvMsgCount >= 
-                    contiguousMsgCountWhichTriggersFlowControl ) {
-                    this->iiu.busyStateDetected = true;
-                }
-                else { 
-                    this->iiu.contigRecvMsgCount++;
+            //
+            // We leave the bytes pending and fetch them after
+            // callbacks are enabled when running in the old preemptive 
+            // call back disabled mode so that asynchronous wakeup via
+            // file manager call backs works correctly. This does not 
+            // appear to impact performance.
+            //
+            unsigned nBytesIn;
+            if ( this->iiu.pCAC()->preemptiveCallbakIsEnabled() ) {
+                nBytesIn = pComBuf->fillFromWire ( this->iiu );
+                if ( nBytesIn == 0u ) {
+                    break;
                 }
             }
             else {
-                this->iiu.contigRecvMsgCount = 0u;
-                this->iiu.busyStateDetected = false;
-            }         
-            this->iiu.unacknowledgedSendBytes = 0u;
-
-            this->iiu.recvQue.pushLastComBufReceived ( *pComBuf );
-            pComBuf = 0;
-
-            // execute receive labor
-            bool noProtocolViolation = this->iiu.processIncoming ( guard );
-            if ( ! noProtocolViolation ) {
-                this->iiu.state = iiu_disconnected;
+                char buf;
+                ::recv ( this->iiu.sock, &buf, 1, MSG_PEEK );
+                nBytesIn = 0u; // make gnu hoppy
+            }
+ 
+            if ( this->iiu.state != iiu_connected ) {
                 break;
             }
 
-            // allocate a new com buf
-            pComBuf = new ( std::nothrow ) comBuf;
-            nBytesIn = 0u;
-            if ( ! pComBuf ) {
-                break;
-            }
+            // reschedule connection activity watchdog
+            // but dont hold the lock for fear of deadlocking 
+            // because cancel is blocking for the completion
+            // of the recvDog expire which takes the lock
+            // - it take also the callback lock
+            this->iiu.recvDog.messageArrivalNotify (); 
 
-            {
-                int status;
-                osiSockIoctl_t bytesPending = 0;
-                status = socket_ioctl ( this->iiu.sock, // X aCC 392
-                                        FIONREAD, & bytesPending );
-                if ( status || bytesPending == 0u ) {
-                    break;
-                }
+            // 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 );
+
+            if ( ! this->iiu.pCAC()->preemptiveCallbakIsEnabled() ) {
                 nBytesIn = pComBuf->fillFromWire ( this->iiu );
                 if ( nBytesIn == 0u ) {
                     // outer loop checks to see if state is connected
@@ -347,19 +293,74 @@ void tcpRecvThread::run ()
                     break;
                 }
             }
+
+            // force the receive watchdog to be reset every 50 frames
+            unsigned contiguousFrameCount = 0;
+            while ( contiguousFrameCount++ < 50 ) {
+
+                if ( nBytesIn == pComBuf->capacityBytes () ) {
+                    if ( this->iiu.contigRecvMsgCount >= 
+                        contiguousMsgCountWhichTriggersFlowControl ) {
+                        this->iiu.busyStateDetected = true;
+                    }
+                    else { 
+                        this->iiu.contigRecvMsgCount++;
+                    }
+                }
+                else {
+                    this->iiu.contigRecvMsgCount = 0u;
+                    this->iiu.busyStateDetected = false;
+                }         
+                this->iiu.unacknowledgedSendBytes = 0u;
+
+                this->iiu.recvQue.pushLastComBufReceived ( *pComBuf );
+                pComBuf = 0;
+
+                // execute receive labor
+                bool noProtocolViolation = this->iiu.processIncoming ( guard );
+                if ( ! noProtocolViolation ) {
+                    this->iiu.state = iiu_disconnected;
+                    break;
+                }
+
+                // allocate a new com buf
+                pComBuf = new comBuf;
+                nBytesIn = 0u;
+
+                {
+                    int status;
+                    osiSockIoctl_t bytesPending = 0;
+                    status = socket_ioctl ( this->iiu.sock, // X aCC 392
+                                            FIONREAD, & bytesPending );
+                    if ( status || bytesPending == 0u ) {
+                        break;
+                    }
+                    nBytesIn = pComBuf->fillFromWire ( this->iiu );
+                    if ( nBytesIn == 0u ) {
+                        // outer loop checks to see if state is connected
+                        // ( properly set by fillFromWire() )
+                        break;
+                    }
+                }
+            }
         }
+
+        if ( pComBuf ) {
+            pComBuf->destroy ();
+        }
+
+        this->iiu.stopThreads ();
+
+        // arrange for delete through the timer thread
+        this->iiu.killTimer.start ();
     }
-
-    if ( pComBuf ) {
-        pComBuf->destroy ();
+    catch ( ... ) {
+        errlogPrintf ("cac tcp receive thread terminating due to a c++ exception\n" );
+        this->iiu.killTimer.start ();
     }
-
-    this->iiu.stopThreads ();
-
-    // arrange for delete through the timer thread
-    this->iiu.killTimer.start ();
 }
 
+
 //
 // tcpiiu::tcpiiu ()
 //
@@ -401,14 +402,6 @@ tcpiiu::tcpiiu ( cac & cac, callbackMutex & cbMutex, double connectionTimeout,
     earlyFlush ( false ),
     recvProcessPostponedFlush ( false )
 {
-    if ( ! this->pCurData ) {
-        throw std::bad_alloc ();
-    }
-
-    if ( ! this->pHostNameCache.get () ) {
-        throw std::bad_alloc ();
-    }
-
     this->sock = socket ( AF_INET, SOCK_STREAM, IPPROTO_TCP );
     if ( this->sock == INVALID_SOCKET ) {
         this->printf ( "CAC: unable to create virtual circuit because \"%s\"\n",