The V4R2 compiler, like the V3R8, V3R9, and V4R1 compilers, must be installed in a PDSE. Also, the Language Environment runtime option XPLINK must be ON whenever you start the compiler. If you start the compiler under batch by using IBMZPLI or under z/OS Unix System Services by using the pli command, the compiler itself ensures that it runs with XPLINK(ON). However, if you are starting the compiler in some other way, you must ensure that XPLINK(ON) is in effect.
Enterprise PL/I V4R2 contains some new options and some old options with new suboptions. However, the defaults for these new options and suboptions produce executable code that is compatible with the code that is produced by the Enterprise PL/I V4R1 compiler (or any of the releases since V3R3).
If you use with PL/I V4R2 the same settings for your compiler options as you used with the V4R1 and Version 3 releases, you can mix code compiled with V4R2 and earlier releases. You do not need to recompile all your code unless you change the setting of a compiler option that changes the program semantics. For example, you can freely change the ARCH or RULES option when mixing objects, but you cannot do so if you change the BACKREG, BIFPREC, or CMPAT options.
The new options and added suboptions are listed as follows: