Do you have MAPS for z/VSE control blocks ?
Explore VSE PTFs RO38160 and RO38161 are of interest.
PTF RO38161 for CA-EXPLORE for VSE r7.1, published in November 2011, updates control block mapping for SCB and PCB in z/VSE 5.1.
re-req PTFs RO15780, RO24740, RO38159 and RO38160 must be applied first. PTF RO38160 also updates control block mapping for SCB and PCB in z/VSE 5.1. And, it has two of the same pre-reqs which are PTFs RO15780 and RO24740. These are included in z/VSE 5.1 support as that’s the release IBM modified and increased the size of the PCB and SCB control blocks.