code: public void setRollbackOnly()
      {
          final boolean isTraceOn = TraceComponent.isAnyTracingEnabled();
          if (isTraceOn && tc.isEntryEnabled()) { // d173022.3
              Tr.entry(tc, "setRollbackOnly", this);
          }
  
          LocalTransactionCoordinator lCoord = getLocalCoord();
          if (lCoord != null) {
              lCoord.setRollbackOnly();
          } else {
              try {
                  txService.setRollbackOnly(); //LIDB1673.2.1.5
              } catch (Exception e) { //LIDB1673.2.1.5 SystemException
  
                  // Shouldn't get here
                  FFDCFilter.processException(e, CLASS_NAME + ".setRollbackOnly",
                                              "556", this);
                  throw new IllegalStateException("No active transaction");
              }
          }
          if (isTraceOn && tc.isEntryEnabled()) { // d173022.3
              Tr.exit(tc, "setRollbackOnly");
          }
      }
docs: Marks the current local or global transaction to be rolled back