> It's less useful than it once was, and I don't see any need to use
> anything other than the default (1) any longer. IEANUC01, IEANUC11 and
> IEANUC21 are logically the same nucleus;
>
> IEANUC01, V=V Nucleus Modules
> IEANUC11, V=R Nucleus Modules, 31 Bit, not used any longer (Look at the
> length of the load module, you'll see that it has almost nothing in it)
> IEANUC21, V=R Nucleus Modules, 64 Bit.
>
> > John Mattson <mailto:[email protected]>
> > December 1, 2015 at 7:16 PM
> > According to zOS MVS System Commands manual....
> > 4. The last character (character 8 of the LOAD parameter) specifies
the
> > alternate
> > nucleus identifier (0-9). Use this character at the system
programmer's
> > direction.
> > If you do not specify an alternate nucleus identifier, the system
> > loads the
> > standard (or primary) nucleus (IEANUC01) and an architectural
extension of
> > the nucleus (IEANUC11 or IEANUC21), unless the NUCLEUS statement is
> > specified in the LOADxx member.
> > Unfortunately they do NOT give an example. In my case I have
> > inherited an HMC with VVVV00T1 as its value. I understand the first 7
> > chars, but does the "1" mean IEANUC01 11, 21, or what?
> > Fortunately "T" turns on Informational messages and I see in the
syslog
> > "IEA091I NUCLEUS 1 SELECTED" and the message is actually useful (for
once)
> > and says that IEANUC01 was selected. I would think that they would
> > just put
> > that in the syslog message, but that would be too easy.
> > My concern is what about the "architctural extension"? I doubt that I
> > would ever want to change this value, but I would like to know just in
> > case
> > I do someday. I think the manual should just SAY "1" is the default
and
> > corresponds to IEANUC01 IEANUC11 IEANUC21 and so on. "2" would be
IEANUC02
> > and so on. I think this is the case but would like verification. And
an
> > update to the manual.
The 8th character of the load parm selects the y in IEANUCxy (so y
represents the logical nucleus number).
IEANUC0y contains the modules loaded regardless of the ARCHLVL.
IEANUC1y contains the additional modules loaded when ARCHLVL=1
(ESA/390 mode, which z/OS does not support after z/OS 1.5)
IEANUC2y contains the additional modules loaded when ARCHLVL=2
(zArchitecture mode, which has been the only choice since z/OS
1.6).
None of these are V=R. There has been no V=R nucleus since the
beginning of MVS/XA.
There is a small DAT-off nucleus loaded from SYS1.NUCLEUS(IEAVEDAT).
The DAT-off nucleus is not V=R.
Since MVX/XA, the only storage which is V=R is the 24-bit low
private storage in a V=R job step, and the prefix page(s).
Jim Mulder z/OS System Test IBM Corp. Poughkeepsie, NY
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