A fix is available
APAR status
Closed as program error.
Error description
If a BMP Region updates more than about 300 Full Function Databases + HALDB Partitions and the BMP Region does not take a checkpoint prior to the IMS Control Region taking a checkpoint, an overlay of CSA storage may occur due to the Type47 Log Record overlaying storage beyond the end of the Log Work Area.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: This apar affects all IMS V12 customers * * running BMP regions and BATCH IMS regions * * that make updates to large numbers of * * databases (242+) during a single commit * * cycle. * **************************************************************** * PROBLEM DESCRIPTION: ABEND0C4, ABEND0Cx, overlays, and * * unpredictable results may occur when * * attempting to write IMS type47 log * * records that include BMP regions or IMS * * BATCH regions that have made updates to * * more than 242 individual databases * * without committing the data. * **************************************************************** * RECOMMENDATION: INSTALL CORRECTIVE SERVICE FOR APAR/PTF * **************************************************************** Type47 log records are written at the end of IMS checkpoints and include region data and a list of changed databases that have not yet been committed for each IMS BMP region. When the list of databases exceeds the capacity of the type47 log area in which they are built, overlays occur when DFSRCP10 attempts to build them. Each partition of a HALDB is considered an individual database and has magnified the issue. The overlays can result in an ABEND0C4 referencing protected storage, but may also overlay storage that is not protected and cause unpredictable problems when the real storage owner attempts to use corrupted data. An additional problem was detected in which type0408 records may overlay storage using the same changed database list that was used in the type47 record. The type0408 records have larger data base entries than the entries for the type47 record. This limits the size of changed database list to what will fit into a type0408 record built in the PSTLOGWA, before an overlay occurs. That limit is reached at 242 databases.
Problem conclusion
GEN: KEYWORDS: XRFTAKEOVER RSRTAKEOVER *** END IMS KEYWORDS *** To prevent the dependent regions from altering more databases than can be built into a type0408 or type47 log record, BMP regions and BATCH IMS regions will be terminated ABENDU0199 if they attempt database updates after reaching the maximum changed database count. This maximum can be estimated by using the following decimal formula: Let N= the decimal number of 1024 byte blocks allocated for IMS Log Data Set Then Changed Database Limit = (64N - 15) Databases As a fail safe to prevent the overlays while building the log records, ABENDU0100 will be issued to terminate IMS if a record will exceed the capacity of the largest IMS Log Record that can be built, based on the IMS Log Dataset allocation (i.e. IMS log block size). However, abending the dependent regions with ABENDU0199 prior to getting changed database lists that are too large to log should prevent the ABENDU0100 from occurring. CODE CHANGES: IPST Added new field PSTDBCNT to contain the DB change list count. ISCD Added new field SCDDBCNT to hold the maximum count of database names that will fit into a type0408 record using the size of the IMS LOG Dataset, defined by the IMS account. DFSFDLS0 Initialize the new SCD field SCDDBCNT. This is accomplished by using SCDLLOGL (max log record size based on the IMS log allocation size, i.e. IMS Log block size), stripping off the type0408 record overhead size, and determining how many database names will fit in the remaining area. DFSXLGI0 Initialize the new SCD field SCDDBCNT in a BATCH IMS System. This is accomplished by using SCDLLOGL (max log record size based on the IMS Log allocation size, i.e. IMS Log block size), stripping off the type0408 record overhead size, and determining how many database names will fit in the remaining area. DFSRDBL0 Update the new PST field, PSTDBCNT, for each new database added to the changed database list. DFSDLA00 ABENDU0199 when attempting a DB altering call when the limit of the changed database list has been reached. DFSFXC50 Reset PSTDBCNT when Phase2 syncpoint has been called. DFSRCP10 Monitor storage while building type47 records. Acquire new storage when the changed database count exceeds the number that can be logged in the present buffer. ABENDU0100-01 when the record cannot be built in the largest IMS Log record based on the IMS Log Dataset allocation size (i.e. IMS Log block size). ABENDU0100-02 when storage cannot be acquired to build type47 records. DFSRBOI0 Added code to acquire and release storage to build a list of databases that fail dynamic backout and must be presented to DBRC. The dynamic storage is also used in building the type0408 log records. DFSST500 Process type0408 log records on a Tracking IMS System when the database list within it will cause overlays building the DBRC VERUOR or UPDUOR list in the PSTLOGWA. This is accomplished acquiring and releasing dynamic storage when needed. DFSRBLB0 Corrected ERE NOBMP and ERE COLDBASE paths to handle large Type0408 log records and SAVUOR calls. Handled these by processing single UORs at a time. Since the changed DB count is limited to the amount that will fit into a Type0408 maximum size log record, there is no problem writing these using the largest logsize, i.e. IMS Log block size (SCDLLOGL). The IMS MESSAGE AND CODES MANUAL will have the following abends documented: U0199 Explanation A BMP or IMS BATCH region has exceeded the count of databases that can be altered within a commit cycle. Programmer Response Insure that BMP or IMS BATCH regions do not make alterations to more databases than will fit in the largest log record allocated for the IMS Log Data Set (i.e. IMS Log block size) without issuing a syncpoint request or increase the IMS Log Data Set size to accommodate the number of changed databases. An estimate of the maximum number of changed databases that will fit into the largest log record can be determined using the following decimal formula: Let N= the decimal number of 1024 byte blocks allocated for IMS Log Data Set (i.e. IMS Log block size) Then Changed Database Limit = (64N - 15) Databases System Action The BMP or Batch Region is abended U0199. Operator Response After correcting the problem, restart the BMP or IMS BATCH region. Module DFSECP20 U0100 Explanation The IMS Control Region has been abended while attempting to build a type47 log record. Reason Code Explanation R15=1 A type47 log record cannot be created because the changed database list of a BMP exceeds the capacity of the log record in which it is to be built. R15=2 An IMODULE GETMAIN request failed to acquire storage to build a type47 log record. Analysis R15=1 This abend should not occur but is added to prevent overlays in the event that BMP or IMS BATCH regions have corrupted database lists that will not fit into IMS log records. R15=2 An IMODULE GETMAIN failed while attempting to acquire storage to build the type47 log record. R10 contains the IMODULE GETMAIN return code. System Action IMS is abended with ABENDU0100 Operator Response After correcting the problem, restart IMS with /ERE. System Programmer Action Contact IBM@Software Support Module DFSRCP10 An addition to ABENDU0369 will be appended as follows: U0369 Module: DFSST500 Explanation: The Tracking IMS in an RSR TRACKER environment has encountered an internal error. Analysis: At the time of the error, R15 contains the return code indicating the condition that caused the ABEND. Return Code (R15): 1 An IMODULE GETSTOR request failed. R10 contains the IMODULE GETSTOR return code. 2 A DFSBCB request failed. R10 contains the DFSBCB return code. System Action: The IMS Tracker terminates with ABENDU0369. System Programmer Response: Contact IBM Support
Temporary fix
********* * HIPER * *********
Comments
POSTREQ PI11430 REPINNED RP14/02/11 (ATXT) TO ADD POSTREQ PI11430 INFO. **** PE14/02/11 PTF IN ERROR. SEE APAR PI11430 FOR DESCRIPTION. ×**** PE14/02/10 FIX IN ERROR. SEE APAR PI11430 FOR DESCRIPTION
APAR Information
APAR number
PM63331
Reported component name
IMS V12
Reported component ID
5635A0300
Reported release
200
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2012-04-25
Closed date
2012-10-30
Last modified date
2014-03-28
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK83101 PM79248
Modules/Macros
DFSAPST0 DFSDLA00 DFSFDLS0 DFSFXC50 DFSRBLB0 DFSRBOI0 DFSRCP10 DFSRDBL0 DFSST500 DFSXLGI0 IPST ISCD
GC18971406 |
Fix information
Fixed component name
IMS V12
Fixed component ID
5635A0300
Applicable component levels
R200 PSY UK83101
UP12/11/21 P F211
Fix is available
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Document Information
Modified date:
14 December 2020