The GCS segment must be unique indeed, it contains SW type storage (that is Shared Write). And access to that SW storage need to be "controlled". GCS has mechanisms to make it possible to avoid programs stepping on each-other. But, these mechanisms provided integrity in a single GCS group. The GCS "Recovery machine" is part of that machanism. So, new GCS group means: new GCS NSS and a new GCS recovery machine. The SW section also makes that a GCS is saved with CLASS R, Restricted, meaning that to use it one needs to be authorised with a NAMESAVE statement in the directory. Otherwise any VM user could issue IPL GCS and start storing things in the SW area, effectively killing VTAM's environment.
The VTAM (and maybe NETVIEW) segments are all SR, Shared Read, meaning all users use the same pages, but they cannot modify (CP and the HW take care of enforcing that). So, one copy is always enough. To be more complete, saved segments can also have EW, Exclusive Read, storage areas, meaning that each user gets it own copy of these section(s). This is the case for CMS, GCS, CMSAMS and CMSVSAM. Exclusive, so no sharing problems and one NSS copy is enough. 2010/10/19 Franz Josef Pohlen <[email protected]> > Thanks Kris, > > I didn't know that 2 VTAMs can use the same VTAM DCSS concurrently. Will > there be no storage problem if the number of defined LUs increases with the > 2nd VTAM or is this possible problem only related to the GCS segment which I > will rebuild as a GCS2 segment and user. > > > kind regards > Franz Josef Pohlen > > Am 19.10.2010 09:48, schrieb Kris Buelens: > >> I don't see any need/benefit to create another VTAM saved segment >> (guessing both VTAMs will use the same VTAM SW level). Having both >> VTAMs use the same segment even saves some real storage, so why do you >> say "to avoid any storage complaints"? >> >> The VTAM segment can even fall inside the DEF STORAGE of the VTAM >> machine (as it does in the default setup): the name of the VTAM SEGMENT >> is listed in the GCS definitions, meaning GCS will load it soon after >> its IPL, and this for all members of thje GCS group, not only for user >> VTAM. >> >> If however you really insist: >> Q NSS NAME VTAM MAP to get the addresses it currently uses >> DEFSEG VTAM2 xxx-yyy SR where xxx-yyy is obtained from Q NSS >> run the VTAMSEG EXEC >> This is outside the VMSES environment, so if you'd apply service to >> VTAM, you'll have to repeat the above. >> >> 2010/10/19 Franz Josef Pohlen <[email protected] >> <mailto:[email protected]>> >> >> >> Hi listers, >> >> my customer uses VM-TN3270E, SCEXIT and Dial to VM-VTAM to connect >> to his CICS-TS in zVSE. Now he is going to reach the 4096 devices >> limit in his vm-vtam, because the Non-SNA resources support only >> 3-digit device numbers. We want to create a 2nd GCS and VTAM with >> its own segments to avoid any storage complaints. I know how to >> build a new GCS, but how can I build a new VTAM NSS VTAM2 instead of >> VTAM. >> -- >> kind regards >> Franz Josef Pohlen >> >> >> >> >> -- >> Kris Buelens, >> IBM Belgium, VM customer support >> > -- Kris Buelens, IBM Belgium, VM customer support
