were located below the line, and the <rest> were located above the line...
Actually, I have heard of two different terms (the line vs the bar):Below the line
: programs that need to be loaded using a 24 bit address.Below the bar
: programs that need to be loaded using a 31 bit address.Above the bar
: programs that are loaded using a 64 bit address.
The load modules (programs) self-identify their loading requirements through the use of the RMODE parameter during the link-edit process. The author of the program determines those settings. You can browse SYS1.LINKLIB and see a variety of combinations of RMODE and AMODE.
When you use any program, the system's loader will load them in the 2G virtual storage. And yes, some of them may be loaded below the line, others above the line, and still others will be loaded above the bar.