Dear Radoslaw
Thanks for your help! it is very clear
I am sorry! I have other questions:
Below is our allocxx
-----------------------------------------------------------------------
CATLG_ERR FAILJOB(YES) /*FAIL THE JOB*/
ERRORMSG(YES) /*ISSUE THE WTO*/
VOLUME_ENQ POLICY(WAIT)
SPEC_WAIT POLICY(WAITNOH)
MAXNWAIT(255)
POLICYNW(CANCEL)
ALLC_OFFLN POLICY(WAITNOH)
MAXNWAIT(255)
POLICYNW(CANCEL)
TIOT SIZE(64) /* SIZE OF THE TASK I/O TABLE */
-------------------------------------------------------------------------
Q1 Is this ALLOCXX correct or not?
Q2 How to display TIOT size in a existing system?
> Could I use Dynamic volume count(DVC) replace the volume count parameter?
In most cases YES.
> assign DVC to every PS dataset
Q3. Could DVC be used for VSAM?
Q4 Do sytem assign DVC to every VSAM dataset ?
Q5.What situation cann't we use DVC replace the volume count parameter?
Thanks again!
Jason Cai
发件人： R.S.
发送时间： 2011-04-25 19:42:54
收件人： IBM-MAIN
抄送：
主题： Re: Could I use Dynamic volume count(DVC) replace the volume count
parameter
W dniu 2011-04-25 09:44, ibmnew pisze:
> Hi all
>
> "Volume count" unconditionally puts that number of entries in the catalog
> for a new data
> set. Dynamic volume count only puts in the volumes that actually get
> extended to and have data on them. This cuts down on the space taken up
> in the catalog.
>
> Q1 Could I use Dynamic volume count(DVC) replace the volume count parameter?
In most cases YES.
> Q2 Is there any other advantage for DVC?
IMHO the most important advantage of DVC is dynamic character - you can
change already existing datasets by changing DATACLASS they have
assigned. No need to ALTER existing datasets file by file. "Regular"
volume count in dataclass is taken only during creation of new dataset.
> Q3 Is there any disadvantage for DVC?
Yes, TIOT size. First idea is to assign DVC to every PS dataset and set
number of volumes to 59. Why not?
However you can reach "JCL limit for number of datasets in single step".
For TIOT set to default 32k it is apporx. 1635 datasets.
A lot, but every volume is counted! So if you use DVC 59, then your
limit is 1635/59 = 27 datasets only!
Solution:
1. Increase TIOT size to maximum, which is 64k
2. Reduce number of volumes in DVC
3. Use DVC only where really needed.
HTH
--
Radoslaw Skorupka
Lodz, Poland
