ABCs of z/OS System Programming Volume 3 - IBM Redbooks

4.25 PDSE enhancements
PDSE, two address spaces
SMXC in charge of PDSE serialization
SYSBMAS, the owner of DS and HS buffering
z/OS V1R6 combines both in a single address space
called SMSPDSE and improves the following:
Reducing excessive ECSA usage
Reducing re-IPLs due to system hangs in failure or
CANCEL situation
Providing tools for monitoring and diagnosis through
VARY SMS,PDSE,ANALYSIS command
Finally, a restartable SMSPDSE1 in charge of all
allocated PDSEs, except the ones in the LNKLST
controlled by SMSPDSE
Figure 4-35 PDSE enhancements
PDSE enhancements
Recent enhancements have made PDSEs more reliable and available, correcting a few
problems that caused IPLs due to a hang, deadlock, or out-of-storage condition.
Originally, in order to implement PDSE, two system address spaces were introduced:
► SMXC, in charge of PDSE serialization.
► SYSBMAS, the owner of the data space and hiperspace buffering.
z/OS V1R6 combines SMXC and SYSBMAS to a single address space called SMSPDSE.
This improves overall PDSE usability and reliability by:
► Reducing excessive ECSA usage (by moving control blocks into the SMSPDSE address
space)
► Reducing re-IPLs due to system hangs in failure or CANCEL situations
► Providing storage administrators with tools for monitoring and diagnosis through VARY
SMS,PDSE,ANALYSIS command (for example, determining which systems are using a
particular PDSE)
However, the SMSPDSE address space is usually non-restartable because of the eventual
existence of perennial PDSEs data sets in the LNKLST concatenation. Then, any hang
condition can cause an unplanned IPL. To fix this, we have a new AS, the restartable
SMSPDSE1, which is in charge of all allocated PDSEs except the ones in the LNKST.
148 ABCs of z/OS System Programming Volume 3