code: @Override
  	// @NotThreadSafe
  	protected void ensureCapacity(long capacity) throws IOException {
  		long curCapacity = pbuffer.capacity();
  		if(curCapacity<capacity) expandCapacity(curCapacity, capacity);
  	}
docs: This class takes a lazy approach on allocating buffer space.  It will allocate
  additional space as needed here, rounding up to the next 4096-byte boundary.