A quick note for Mainframe Assembler programmers...
Mr. Don Higgins developed some years ago a PC suite, called PC/370, to
assemble, and linkedit mainframe assembler source code and create small
MS-DOS executables.
More recently he developed a J2SE (JRE 6.0+) HLASM Compatible Mainframe
assembler, linker and emulator that runs on Windows and Linux.
It is Open Source (java) and freely downloadable from
http://www.z390.org