Space allocation strategies

When UIE opens a data set for the first time, z/OS allocates the space that you have specified for your primary allocation.

z/OS uses up to five noncontiguous extents on the DASD volume to satisfy your request. If z/OS uses your secondary allocation, it can look for up to 16 total extents on the same volume, including those used on the primary request. The amount of space needed by each data set can vary significantly depending on your environment.

Related topic

Processing-performance-data

If you do not want to use large amounts of temporary space while the UIE batch job is running and your temporary volumes have a lot of free space available, you can assign a small primary allocation and a large secondary allocation for each temporary data set group. However, this strategy entails the risk of getting an x37 ABEND if one of the volumes has space for the primary allocation, but not for the secondary extents.

If you have a lot of temporary space, but you are not sure how full each volume is, assign your primary allocation a value that is close to the total space you will need and make your secondary allocation a small value. If z/OS cannot find enough free space, your job will abend very quickly and you can change one of the dynamic allocation parameters on the Datasets panel to access more temporary storage. For more information, see Handling-data-set-storage-errors-x37-abend.

 

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