Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is an older version of Boost and was released in 2018. The current version is 1.89.0.

zlib::z_params::next_out

A pointer to the next output byte.

void * next_out;