SETSMS command to alter the setting of USEEAV

You can use the SETSMS command to change the setting of USEEAV without having to re-IPL. This modified setting is in effect until the next IPL when it reverts to the value specified in the IGDSMSxx member of PARMLIB. To make the setting change permanent, you must alter the value in SYS1.PARMLIB.

The syntax of the operator command is:
SETSMS USEEAV(YES|NO)

The USEEAV(NO) setting indicates that no new primary space allocations or extended data sets to a new volume are allowed on an EAV.