IBM z/OS manual CICS/VSAM enabled for 24x7 availability, JES2 and JES3, System Management Services

availability. This form of clustering, known as single system image, also provides tremendous scale. Up to 32 zSeries servers with z/OS can appear as a single image for

data sharing applications (see previous section, Parallel Sysplex Clustering Technology).

CICS/VSAM enabled for 24x7 availability

DFSMS Transactional VSAM Services (DFSMStvs) allows you to share VSAM data sets across CICS, batch, and object-oriented applications on z/OS or distributed sys- tems. DFSMStvs can enable concurrent shared updates of recoverable VSAM data sets by CICS transactions, mul- tiple batch applications, and 24-hour availability of CICS and batch applications. DFSMStvs is built on top of VSAM record-level sharing (RLS), which permits sharing of recov- erable VSAM data sets at the record level.

System-Managed CF Structure Duplexing

System-Managed Coupling Facility (CF) Structure Duplex- ing is designed to signifi cantly enhance Parallel Sysplex availability. It can provide a robust failure recovery capa- bility via CF structure redundancy, and it can enhance Parallel Sysplex ease of use by helping to reduce the complexity of CF structure recovery. These benefi ts can be achieved by creating a duplicate (or duplexed) copy of a CF structure and then maintaining the two struc- ture instances in a synchronized state during normal CF operation. In the event of a CF related failure (or even a planned outage of a CF), failover to the remaining copy of the duplexed structures can be initiated and quickly com- pleted transparent to the CF structure user and without manual intervention.

JES2 and JES3

JES2 and JES3 handle the submission of work and the distribution of output for the Base Control Program. JES2 exercises independent control over its job processing functions, whereas JES3 exercises centralized control.

•In z/OS 1.2, JES2 and JES3 allow an installation to have up to 999,999 jobs managed at any single point in time. In addition, both provide the installation the ability to obtain (spinoff) their JESlog data sets prior to job com- pletion.

•The JES2 Health monitor, in z/OS 1.4, provides improved diagnostics. Even when JES2 is not responding to com- mands, the JES2 monitor, running in a separate address space, will be able to provide information about JES2’s status. JES2 also provides enhanced recovery from cor- rupted checkpoint data to prevent multisystem outages

•In z/OS 1.4, JES3 provides additional tolerance for ini- tialization errors and the MAINPROC refresh function which enables the dynamic addition of systems to the sysplex.

System Management Services

z/OS Version 1 Release 6 base elements

HCD

SMP/E

Managed System Infrastructure for Setup

Managed System Infrastructure for Operations

z/OS Version 1 Release 6 optional priced features

RMF

SDSF

HCM

61