MailStream Plus Zone Matrix file doubled in size with the May 2018 USPS data.

MailStream Plus™ on z/OS platform
Per the May 2018 database notification-
The Zone Matrix File (PRFZONES.MSP) has doubled in Size. This is due to the Addition of the new inbound’ Military mail Zone changes outlined in the 4/23/18 Federal Register Notice (FRN) at
Zos Customers might need to increase their file allocation size for the Zone Matrix

With the increase in size of the USPS's Zone Matrix file in May 2018, z/OS users will need to increase the number of cylinders for the USPSRFZM file.
•   If loading from Internet Download-
 Make the change to the DD USPSRFZM in the MSPALOCF JCL (which is used to allocate the flat files into which the downloaded files are first FTP'd into).   
 And make the change in the Define Cluster for the USPSRFZM VSAM file in the MSPDBIND JCL, which is where the flat files then get loaded into (which MailStream Plus™ actually uses.)  The increases should be made in the DATA section and the INDEX section

With the February 2019 files, the size went back down to much what it was before.  (The increase had been due to the USPS including a bunch of data that wasn't needed in the file.)

But the Developers said that we are leaving the larger as-is, at least now now, since the USPS might increase the size again.
UPDATED:  March 15, 2019