code: @Override
      public void setBufferSize(int size) {
          if (this.writing || isClosed()) {
              throw new IllegalStateException("Stream unable to set size");
          }
          this.amountToBuffer = size;
          this.bbSize = (49152 < size) ? 32768 : 8192;
  
          // make sure we never create larger frames than the max http2 frame size
          Integer h2size = (Integer) this.getVc().getStateMap().get("h2_frame_size");
          if (h2size != null && h2size < bbSize) {
              this.bbSize = h2size;
          }
  
          int numBuffers = (size / this.bbSize);
          if (0 == size || 0 != (size % this.bbSize)) {
              numBuffers++;
          }
          this.output = new WsByteBuffer[numBuffers];
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "setBufferSize=" + size + "; " + this);
          }
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.ws.http.channel.internal.outbound.HttpOutputStream#setBufferSize(int)