code: final LocalTransactionCoordinator suspendLocalTx()
      {
          final boolean isTraceOn = TraceComponent.isAnyTracingEnabled();
          if (isTraceOn && tc.isEventEnabled())
          {
              LocalTransactionCoordinator currentLTC = ltcCurrent.getLocalTranCoord();
              if (currentLTC != null)
              {
                  Tr.event(tc, "Suspending LTC cntxt: tid=" + Integer.toHexString(currentLTC.hashCode()) + "(LTC)");
              }
          }
  
          LocalTransactionCoordinator suspendedLocalTx = ltcCurrent.suspend();
  
          if (isTraceOn && suspendedLocalTx != null && TETxLifeCycleInfo.isTraceEnabled()) // d171555
          {
              TETxLifeCycleInfo.traceLocalTxSuspend("" + System.identityHashCode(suspendedLocalTx), "Suspend Local Tx");
          }
  
          return suspendedLocalTx;
      }
docs: Suspend the current local transaction. If no local transaction exists
  on the current thread, do nothing.