In addition to initializing system areas, MVS™ creates
address spaces for system components. MVS establishes an
address space for the master scheduler (the master scheduler address space) and other system address
spaces for various subsystems and system components. Some of the component address spaces are listed
in Table 1.
Table 1. Partial list of component address spaces
Address space
Description
*MASTER*
Master address space
ABARS, ABARxxxx
1 to 15 DFSMShsm
secondary address spaces to perform aggregate backup or aggregate recovery processing.
ALLOCAS
Allocation services and data areas
ANTMAIN
Concurrent copy support
APPC
APPC/MVS component
ASCH
APPC/MVS scheduling
CATALOG
Catalog functions. Also known as CAS (catalog address space).
BPXOINIT
z/OS UNIX System Services
CONSOLE
Communications task
DFM
Distributed File Manager
DFMCAS
Distributed File Manager
DLF
Data lookaside facility
DUMPSRV
Dumping services
HSM
DFSMShsm
HZSPROC
IBM® Health Checker for z/OS®
FTPSERVE
FTP servers; can be user-specified names.
GDEDFM
For each Distributed File Manager/MVS user conversation that is active, an
address space named GDEDFM is created.
GRS
Global resource serialization
IEFSCHAS
Scheduler address space
IOSAS
I/O supervisor, ESCON, I/O
recovery
IXGLOGR
System logger
JES2
JES2
JES2AUX
JES2 additional support
JES2CIxx
1-25 JES2 address spaces used to perform z/OS converter and interpreter functions
JES2EDS
JES2 Email Delivery Services (EDS)
JES2MON
JES2 address space monitor
JES3
JES3
JES3AUX
JES3 additional support
JES3DLOG
JES3 hardcopy log (DLOG)
JESXCF
JES common coupling services address space
LLA
Library Lookaside
NFS
Network File System address space
OAM
DFSMSdfp Object
Access Method (OAM). In a classic OAM configuration, there may
be one address space to perform tape library and/or object processing; in a multiple OAM
configuration there may be multiple Object OAM address spaces and/or a Tape Library OAM address
space.
OMVS
z/OS UNIX System Services
OTIS
DFSMSdfp Object
Access Method (OAM) Thread Isolation Support. In either a classic OAM configuration or a multiple
OAM configuration, there might be one address space to perform object-related processing and enable
subsystem deletion.
PCAUTH
Cross-memory support
PORTMAP
Portmapper function
RASP
Real storage manager (includes support for advanced address space
facilities)
RMM
DFSMSrmm
RRS
Resource recovery services (RRS)
SMF
System management facilities
SMS
Storage management subsystem
SMSPDSE1
Optional restartable PDSE address space. If the SMSPDSE1 address space is
started, SMSPDSE manages PDSEs in the LINKLST concatenation and SMSPDSE1 manages all other
PDSEs.
SMSVSAM
VSAM record level sharing
TCP/IP
TCP/IP
TRACE
System trace
VLFf
Virtual lookaside facility
XCFAS
Cross system coupling facility
VTAM
VTAM
WLM
Workload management
Figure 1. Virtual storage layout for multiple address spaces
Address spaces differ in their ability to use system services depending on whether the address
space is a limited function or full function address space.
Limited function address space
If the specific initialization routines provided by the
components that use IEEMB881 enter a wait state, pending Master Scheduler Initialization, STC does
no additional address space initialization. Thus, the functions that component address spaces can
perform are limited. Components with limited function address spaces cannot:
Allocate data sets.
Read JCL procedures from SYS1.PROCLIB.
Allocate a SYSOUT file through the Job Entry Subsystem.
Use some system services because the components frequently run in cross memory mode.
Full function address space
If, after a component completes its own initialization, it
returns to IEEPRWI2 and completes STC processing, the address space is fully initialized. Such an
address space is called a full function address space.
The component creating a full function address space does not need to provide a procedure in
SYS1.PROCLIB. If specified to IEEMB881, a common system address space procedure, IEESYSAS, will
invoke a specified program to run in the address space.
For example, if a full function address space called FFA is to be started using the module
IEEMB899, the component would ordinarily need to supply a procedure of the following form:
//FFA PROC
// EXEC PGM=IEEMB899
The procedure will be invoked as follows:
//IEESYSAS JOB
//FFA EXEC IEESYSAS
The procedure IEESYSAS consists of the following statements:
