[ncmncm]

This sort of facility is the reason why C++ iostreams (technically, std::ios_base) support a primitive array type and static index allocator, via members iword/pword and xalloc. It is not often used, but where used it would be hard to do anything else.

https://en.cppreference.com/w/cpp/io/ios_base

It is quite common for a stream object to thread a call chain from top to bottom, for independent reasons. So, ability to stick on other context has saved bacon fairly often, over the decades.