I have no knowledge on Mainframe Assembler. And planning to learn Mainframe Assembler basics at least. Like below..
1. Structure of Mainframe Assembler language
2. Different registers and their usage using examples with explanations
3. Different mainframe assembler instructions with examples
4. Simple and Sample mainframe assembler programs (Adding two numbers,Simple loops..etc)
I have got some manuals from google but they are not specific to mainframe.