code: public synchronized void changeInitialWindowSizeAllStreams(int newSize) throws FlowControlException {
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "changeInitialWindowSizeAllStreams entry: newSize: " + newSize);
          }
          this.initialWindowSize = newSize;
  
          H2StreamProcessor stream;
          for (Integer i : streamTable.keySet()) {
              stream = streamTable.get(i);
              stream.updateInitialWindowsUpdateSize(newSize);
          }
      }
docs: Update the initial window size for all open streams. Additionally, call updateInitialWindowsUpdateSize()
  on each stream to notify it of the increase (and possible write out queued data)
  
  @param int newSize
  @throws FlowControlException