On Mon, 21 Apr 2014 15:31:31 -0500, Paul Gilmartin  wrote:

>z/OS engenders enormous obstacles to migrating to an all 64-bit LE enabled
>universe.

Yes. Not the least of which is that the LE direction is to support 64-bit code 
only with XPLINK, and that there is no mechanism in LE for a non-XPLINK program 
to call an XPLINK program

The design of XPLINK and XPLINK-64 currently precludes the mixing of the two. 
That means that the only migration from 31-bit code to 64-bit code in LE is to 
replace entire executable units, including all called programs, at the same 
time.

IMO, the LE designers did a poor job when they designed XPLINK-64. In contrast, 
the MVS designers did a good job designing the calling conventions for 64-bit 
programs. 64-bit programs can easily be written to interoperate with 31-bit 
programs, and the 31-bit applications do not need to be changed to be able to 
work with 64-bit applications, provided that the 64-bit applications are 
designed with interoperability in mind. LE did not consider any such 
possibility or need.

-- 
Tom Marchant

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