Which CCUWPARM member controls the FILES Block Length

Document ID : KB000124138
Last Modified Date : 04/01/2019
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Question:
Running with CA-Disk V12.5 under z/OS V2.2 I recently re-created my Files Dataset to resize it to a larger size. The prior file had a Block Length of 447744, but I noticed that after the resizing the Files Dataset had a block length of 111872, which is not what I expected. I am assuming that there is a member in the CCUWPARM file that sets these values, but I can not find it. Is the 111872 a default Block Length? I don't know where that came from? Please advise me on where this setting should be designated.
Answer:
The "BLOCK LENGTH" field shown in the FILESTAT report is internally managed, the user has no control of that value. 
It varies depending on the number of records specified in the FILEDEFN member of CCUWPARM.
The PHYSICAL BLOCK SIZE value should always be 27998.