Default buffer size of class basic_filebuf

[Weber, Peter (Wilken GmbH)]

Thanks for your answer, seems I figured it out. I always thought I can't
be in the file fstream and fstream.tcc -> but exactly there is
everything I want to know.

// from fstream
#include <istream>
#include <ostream>
#include <bits/codecvt.h>
#include <cstdio>             // For BUFSIZ

...
...
...
      /**
       *  Actual size of internal buffer. This number is equal to the
size
       *  of the put area + 1 position, reserved for the overflow char
of
       *  a full area.
       */
      size_t			_M_buf_size;


// from fstream
  template<typename _CharT, typename _Traits>
    basic_filebuf<_CharT, _Traits>::
    basic_filebuf() : __streambuf_type(), _M_lock(), _M_file(&_M_lock),
    _M_mode(ios_base::openmode(0)), _M_state_beg(), _M_state_cur(),
    _M_state_last(), _M_buf(0), _M_buf_size(BUFSIZ),
    _M_buf_allocated(false), _M_reading(false), _M_writing(false),
_M_pback(), 
    _M_pback_cur_save(0), _M_pback_end_save(0), _M_pback_init(false),
    _M_codecvt(0), _M_ext_buf(0), _M_ext_buf_size(0), _M_ext_next(0),
    _M_ext_end(0)
    {
      if (has_facet<__codecvt_type>(this->_M_buf_locale))
	_M_codecvt = &use_facet<__codecvt_type>(this->_M_buf_locale);
    }


Thanks for your patience. Anything I should keep in mind?
Bye