To improve performance, the XL Fortran run-time library has its own buffers and its own handling of these buffers. This means that mixed-language programs cannot freely mix I/O operations on the same file from the different languages. Mixing code compiled by multiple Fortran compilers, for example xlf and g77, could face similar problems. The safest approach is to treat the code compiled by another Fortran compiler as non-Fortran code. To maintain data integrity in such cases:
As an alternative to calling the flush_ procedure, you can use the buffering run-time option to disable the buffering for I/O operations. When you specify buffering=disable_preconn, XL Fortran disables the buffering for preconnected units. When you specify buffering=disable_all, XL Fortran disables the buffering for all logical units.