How can I learn the business logic of my job?

[Atari2601]

Good evening. My main language is Spanish, so I hope you understand what I want to say.

I have been working with mainframe technologies for many years in banking and currently the insurance sector. After 5 years as a programmer, I have been asked what I need to learn the business aspect of my job. Can you give me some ideas of good practices I should do to learn and keep the knowledge of the insurance sector?

I know the technical aspect, I mean I know PL/I, JCL, DB2, our client tools, but I easily forget the concepts of the products I develop after some time. I stop using them, I have other assignments, then after a year a product comes back and I need to check my notes to remember. Then I notice I lost some notes.

I struggle every time they ask us to give evidence of the numbers we produced in our batch. I normally can give little input and my analyst answers 90% of the emails.

I think could start compiling old emails with the calculations my analyst used to answer the emails, take my old notebooks and start a clean compilation.

Can you give me any other idea how to get more knowledge of the business aspect of my job?