CXXMAINT (Maintain Directory) › CXXMAINT ALTER OPTION2= (Activating Other Features) › CXXMAINT ALTER OPTION2=areaev (Data Area Extent Validation) › When to Use

When to Use

Use this option when you want to turn on or turn off data area data set extent validation.

CA Datacom/DB uses data set extent validation in the following way. When a data area is not open, users can and sometimes do move the current extents to more extents, less extents, or different volumes. The data set may even be uncataloged and then recataloged to add volumes. All tracks of the data set would not be correctly preserved if a mishap should occur during the moving of current extents. CA Datacom provides a certain amount of protection to avoid the data corruption such mishaps could cause. This option provides even more protection by performing the following steps.

After the open of a data area, the control block is read and verified. The last block on the last track of every extent is then read. This read validates that the block exists and is of the proper size. It is not, however, validated to look proper in content. This option also places a control block as the last block of the data set. It is built during the LOAD or REORG load and moved during an EXTEND or dynamic extend. If this option is turned on, the open process verifies it is correct.