<ignorance level warning>
I never programmed any VSAM I/O. I never took the time to read much about VSAM 
internals.
</ignorance level warning>

I'm trying to understand SHAREOPTIONS. Read parts of DFSMSdfp using data sets, 
VSAM demystified, and the IDCAMS reference. Some became clear, some not. Here 
are some Qs to help me with the latter.

- I could not find what the defaults are, if no SHAREOPTIONS are specified with 
the DEFINE CLUSTER? I cannot try myself because SMS forces me to a dataclass 
that has them specified.

- Similarly, what is the default if only the "cross-region" option is specified 
but not the "cross-system"?

I understand that the highest option level to be used with a specific 
application is determined by the application, how it is coded. The higher the 
level, the less VSAM helps to ensure data integrity.

- Using a lower level than what the application supports, may negatively 
influence application parallelism. Using a higher level however jeoardizes data 
integrity. Is this correct?

- What is the possible negative impact when a cluster is defined with 
SHAREOPTIONS(3) when the application asks for SHAREOPTIONS(3,3)? I understand 
the CBUF function would not be active. What happens to the applocation. Will it 
just fail? Would it depend on te programmer and whether he/she cared to handle 
this situation in te application?

Thanks
--
Peter Hunkeler

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