There was a library written in Fortran called CERNLIB which included a broad variety of miscellaneous numerical algorithm implementations (e.g. minimization, integration, special functions, random number generation) [1]. I couldn't tell you exactly when the library was first released, but my best guess would be the early 80s. It can't possibly be later than 1986 when PAW was initally released [2]. The field has since transitioned from the Fortran based PAW to the C++ based ROOT since then, but many high energy collaborations still rely on CERNLIB for their own analysis frameworks (keep in mind that many of these experiments had been in planning and development stages for over a decade before they actually turned on).
The thing about this that I find interesting is that compiling CERNLIB has become a lost art and that this fact has had far reaching consequences. The last available binaries were compiled with GCC 4.3 in 2006 and packages are only available for Scientific Linux 4 [3]. This crucial dependency has led to collaborations using extremely outdated Linux distributions and GCC versions in their computing facilities. The majority of analysis code is written in C++, but not even C++11 additions can be used because everything is frozen on GCC 4.3. Nobody can even run the analysis environment on their local machines without resorting to the use of virtual machines running SL4. It was really a nightmare to deal with.
[1] - https://en.wikipedia.org/wiki/CERN_Program_Library
[2] - https://en.wikipedia.org/wiki/Physics_Analysis_Workstation