DFSVSMxx member of the IMS PROCLIB data set

Use the control statements in the DFSVSMxx member of the IMS PROCLIB data set to define settings for buffer pools, trace options, coupling facility structures, IRLM lock timeout, and transactions in a HALDB partition.

In an IMS batch system, these control statements are put in a data set with ddname DFSVSAMP. The data set must contain blocked or unblocked 80-character records.

Recommendation: Do not place DFSVSAMP in the same PDS as your user application files. This causes batch jobs to abend with ABEND0C4 in DFSRTM00.

In an IMS online system, these control statements are put in the IMS.PROCLIB data set in member DFSVSMxx. The VSPEC symbolic parameter in the IMS, DBC, and DCC procedures is used to specify the suffix (xx) of the DFSVSMxx member to be used. During stage 2, IMS creates a default member with suffix 00. If a suffix in not specified on the startup procedure, the default member is used. The default values are also used if the control statements in the startup procedure are missing or invalid.

The control statements in this member are processed during IMS initialization. The control statements allow you to perform various tasks.

Table 1. DFSVSMxx parameters for Online IMS that can be specified in IMS batch jobs via DFSVSAMP DD.
DFSVSMxx member of the IMS PROCLIB dataset	DFSVSMxx	DFSVSAMP
Defining Fast Path DEDB buffer pools for single-area structures	Yes	No
Defining Fast Path DEDB buffer pools for multi-area structures	Yes	No
Defining VSAM buffer pools	Yes	Yes
Defining VSAM subpools	Yes	Yes
Defining VSAM performance options	Yes	Yes
Defining OSAM subpools	Yes	Yes
Requesting that z/OS dynamic allocation use extended storage	Yes	No
Specifying sequential buffering for an online system	Yes	No
Defining serviceability and trace options	Yes	Yes
Defining DL/I call image trace	Yes	Yes
Defining DASD logging initialization parameters*	No	No
Defining IMS batch without dynamic allocation	No	Yes
Disabling the re-opening of databases after an IMS restart	Yes	No
Defining coupling facility structure names for sysplex data sharing	Yes	Yes
Using the coupling facility for OSAM data caching	Yes	Yes
Enabling the long busy handling function	Yes	No
Enabling the IRLM lock timeout function	Yes	Yes
Preventing transactions from being terminated when HALDB partitions are unavailable	Yes	No
Preventing DBRC calls for HALDB version verification	Yes	Yes
Resuming an online reorganization for HALDBs during IMS warm or emergency restart	Yes	No
Discarding preallocated SDEP control intervals	Yes	No
Preventing a /DBRECOVERY command for a database that has INDOUBT EEQEs	Yes	No
Removing the limit for the number of DFS3314W messages issued	Yes	Yes

*The DASD logging initialization parameters have moved to the LOGGER section of the DFSDFxxx member of the IMS PROCLIB data set.