Question about REALMEMSIZE option

[juanvg1972]

I have a question about REALMEMSIZE option.

Definition says: Some SAS procedures use the REALMEMSIZE option to specify how much virtual memory the procedure can allocate and use without inducing excessive page swapping.

Then, I suppose is a parameter to control page swapping and to avoid excessive page swapping.

How does it prevent swapping??,

If the systems needs more memory than real memory available, then it starts to swap until the total memory reach the value of REALMEMSIZE, is correct??.
Is a limit value for the page swapping??

Any information about REALMEMSIZE working will be greatly apreciatted.

Thanks in advance.

 

[ChrisW75]

I believe it limits the amount of data loaded into memory at a time for processing. If you load more data into memory that you can can hold, you'll get alot more pageswapping (ie swapping from physical to virtual memory). For instance Proc sort will work in chunks, and the size of the chunks will depend on how much memory is allocated. That's the way I've always interpreted it anyway.

Chris
Business Analyst, Code Monkey, Data Wrangler.
SAS Guru.