Minutes of the UK GSE CICS-DBCTL meeting

IBM South Bank, 5 November 1998

Chairman:Ian Tyson- 01403 232329

Secretary:Neil Price- 01827 710702

Administration

Ian opened the meeting and welcomed the other 13 delegates (list attached) plus Steve Ferguson of Software Products.

It was generally agreed that a meeting should be held next year, possibly earlier than November. The spring meeting of the main IMS group may again be a database-oriented one of interest to DBCTL users.

Ian mentioned that he no longer works with DBCTL and so might not be the right person to organise these meetings. This will be discussed at the IMS Working Group steering committee meeting on 2 December.

Peter Armstrong of BMC Software has written a new DBRC book, but Ian hadn’t yet received a copy.

Minutes / Matters arising

The minutes of the meeting held on 20 November 1997 were accepted and approved. Those of the joint meeting with the IMS group on 18 March 1998 were accepted.

There were no matters arising from these.

New Members/Attendees

Origin-IT was represented for the first time, the delegates being Trevor Wellings, Mick Lofthouse and Bram Dorreman.

Frank Fleming represented Barclays Bank. Frank is chairman of the UK GSE IMS Working Group but had not previously attended a CICS-DBCTL subgroup meeting.

Other new attendees were Dave Williams from ITT London & Edinburgh Insurance, and Anne Joyner and Ann Wareing from C.S.C.

Federal Mogul I.T. has recently bought AE Systems, hence Rosalind McNeill’s new details. The telephone number remains unchanged.

What's New from IBM - Peter Sadler

Education

Neil Price (TNT) raised the point that there seems to be no training specifically suitable for new staff in a DBCTL environment. The introductory classes include a lot of unwanted IMS TM information and there seems to be no self-study material. Peter suggested that customers, and this group in particular, need to make IBM Education aware that there may be a demand for such courses. He also mentioned that it is planned to produce an updated IMS Primer, to be available early next year.

As always, Peter listed all CICS and IMS classes, both forthcoming and on-demand, of possible interest.

Recent Product Announcements

IMS Partition DB Version 2 (5697-D85) allows partitioning of indexes.

The IMS/ESA Year 2000 Exit Tool (5697-E04) and IMS Recovery Saver (5665-A68) are both covered later.

IMS/ESA DBRC Security Tool ensures that the RECON datasets are protected from unauthorised operations

Dougie Lawson also mentioned that the IMS Database Control Suite, which he presented at the March meeting, is now GA. This generates all the JCL necessary to maintain your DL/1 databases. It supports third-party utilities such as those from Neon and BMC.

Documentation

Peter specifically recommended the IMS/ESA Version 5 Performance Guide (SG24-4637). He also mentioned that only the ‘-01’ version of the IMS/ESA Version 6 Guide should be used – any copies of the ‘-00’ version (listed on his foil) should be discarded.

Conferences

Free S/390 IMS, DB2 and CICS Symposium entitled "Moving Towards the 21st Century", 2 December, London.

The 1999 IMS and DB2 European Technical Conference will be held from 12 to 16 April in Paris.

Additional items from the IMS Working Group meeting on 3 December

Several IMS-related Computer-Based Training (CBT) courses, mainly aimed at programmers, are available at IBM Learning Centres. Contact your nearest Learning Centre or IBM Education.

IBM now recommends PTR=NT for HIDAM roots.

IBM is also looking for customers to perform early testing on the IMS Version 6 ODBA interface.

CICS/DBCTL Performance Monitoring – Steve Ferguson, Software Products.

Software Products is the UK vendor for Landmark Systems’ products, which include The Monitor (TMON) for CICS, TMON for MVS and TMON for DB2, and now TMON for DBCTL. These are all part of "Performance Works for MVS". TMON for DBCTL interacts with the other products through the NaviGateâ feature.

Steve summarised some of the problems arising when DBCTL replaces Local DL/1, such as the loss of detailed DL/1 statistics and the difficulty of tying together the CICS and DBCTL units of work. When problems occur, the CICS Systems Programmers can rightly say it’s "not a CICS problem". He also mentioned the possibility of increased system contention, firstly due to the additional TCBs and address spaces and secondly due to other CICS systems which would doubtless share the same DBCTL subsystem. He then presented the product, mainly through example screens.

TMON/DBCTL aims to provide Complex "Root Cause" Analysis, including drill-down to MVS causes. Front-end screens allow selection of subsystems, possibly across multiple MVS systems. The Primary Menu then presents various functions. This includes historic analysis, which uses offline "open" format archive data for batch reports through TMON’s own programs or another tool such as SAS. There’s ITASK and IRLM wait/contention analysis – TMON searches IRLM for lock and wait information – and SAP (Save Area Prefix) displays including Abnormal Wait SAPs.

Navigation from TMON/CICS is via task details (N.B. RTKN ties up with the DBCTL Recovery Token) then via the DL1 field into TMON/DBCTL. Similarly in the DBCTL monitor you can go from a volume serial to the relevant TMON/MVS screen, or with a Recovery Token and CICS id to TMON/CICS. Each "navigation point" is highlighted if the relevant target product is installed. For historic data, some synchronisation of history files is required between the various monitors.

Hit rates ("Retrieval Efficiency") are calculated for various buffer pools. Exception monitoring, including the automatic links to relevant TMON screens, can be customized and also includes a "change of shift" capability. For application design verification and diagnosis there’s a PSB Tracking feature and DL/1 Call Activity reporting.

Problems / Hints & Tips/ Requirements

Ian Tyson (IBM) had a problem recently where the IMS subsystem stopped processing because IMS ran out of online log datasets (OLDS). The log archiving jobs had not run because of a lack of initiators. Ian proposes raising a requirement to change log archive to operate independently of job queues, possibly as a subtask in the control region (like DB2) or maybe as a started task in a separate address space.

Dougie Lawson (IBM) mentioned that the DB2 subtask approach suffers from the problem that if archiving ABENDs then only a restart of DB2 will get it going again. Also note that DBCTL will still respond to commands when all online logs are full (e.g. /START OLDS), unlike IMS TM.

Neil Price (TNT) asked if anyone had a way of automatically starting the IRLM when IMS starts, in a similar way as for DB2 (which starts its own IRLM). He uses a member named xxxxSAS in the IMS PROCLIB dataset containing something like ‘S xxxxSTRT’; procedure xxxxSTRT then issues start commands for both the SAS and IRLM regions. Frank Fleming (Barclays) uses automation to trap the "waiting for IRLM" message (DFS039A). Presumably the IRLM could also be included in the IPL start-up list.

Neil also asked if anyone else uses OSAM, as he’s thinking about requirements for OSAM Sequential Buffering. Nobody did. Pete Sadler suggested that maybe people don’t know what it is. (For anyone who doesn’t, it’s an alternative to VSAM ESDS for HD databases).

For the Hints and Tips list see http://web.ukonline.co.uk/dougie.lawson/gse.

IMS/ESA Year 2000 Exit Tool - Peter Sadler (IBM)

Pete covered the Year 2000 problem in general, prompting some discussion. Dougie Lawson thought that 9/4/1999 might be interesting as it’s 99099 (also his birthday - X’24’!). 9/9/99 could also be a problem.

The IMS/ESA Year 2000 Exit Tool helps you work with 2 digit years in your data without a lot of application changes. It specifically addresses collation sequence issues (particularly for segment keys) by use of a windowing technique. It provides an exit routine for a new IMS Data Conversion User Exit provided through V5 APAR PQ14745. The exit is called twice, at entry to and exit from each DL/1 call

Implementation requires unload (without the exit) and reload (with the exit active) of the affected databases. A fixed "date window" is installed into the exit. If variations are required, you could run your own exit code to deal with the exceptional cases, then call the supplied exit for the remainder. The exit is supposed to handle all "standard" date formats.

The DBD parameter DATXEXIT=YES is not required, but is recommended as documentation. If the exit routine exists, it will be called for every database.

The general feeling was that this had come far too late in the day for most people. Also data intercepted by Change Data Capture (for DpropNR etc.) is in the encoded format.

IMS/ESA Recovery Saver - Peter Sadler (IBM)

IMS Recovery was designed to cater for media failure, which implies recovery up to the current time. Timestamp recovery is therefore limited in functionality and has major restrictions.

Timestamp recovery is almost always used for application error recovery. However, it’s governed by system conditions, particularly the requirement for the end of a SLDS (archive log) when the database isn’t allocated. Thus a recovery point almost never exists when one is needed. Often there’s also the problem of co-ordinating IMS and DB2 recoveries.

IMS/ESA Recovery Saver "conditions" a set of IMS logs and a copy of the RECONs to indicate that IMS activity ceased at a specific timestamp. Note that copies of the logs and RECONs must be used! Afterwards the recovery is recorded in the real RECONs.

This procedure also allows Timestamp recovery to work in a Data Sharing environment.

For DB2 co-ordinated recovery, the recommendation is to recover the DB2 objects to any valid point and then use Recovery Saver to recover the IMS data to the same timestamp.

Discussion – Resource Measurement and Chargeback

See the CICS-IMS Database Control Guide (SC33-0660 for 3.3, SC33-1184 for 4.1) for general information and the CICS Customization Guide (SC33-0665, SC33-1165) for details.

Rosalind McNeill (Federal Mogul) described the differences between Local DL/1 and DBCTL measurement using CMF:

With CICS 4.1 it is possible to cut records at timed intervals for long-running tasks.

Nobody seems to know what units are used for the TCB CPU fields.

Note that TMON requires CICS tracing to be active.

Mick Lofthouse (ORIGIN-IT) queried the large increase (around 30%) in CICS CPU time due to conversion from Local DL/1 to DBCTL. Discussion included the possibilities of latent demand and double accounting (see also the previous minutes where the percentage of CPU attributed to DBCTL tasks was queried). Because chargeback is based on CPU, it may be necessary to adjust the charging rate to compensate.

It was suggested that an expert in this area (perhaps from Hursley) could be invited to a future meeting.

Open Forum – Avoiding Action

Ian Tyson drew attention to IBM INFO APARs, which contain a lot of useful information. These can be searched and viewed on Dial-IBM or on the IBM software support Website. There will shortly also be a new IBM Web page for the UK which will be an alternative to Dial-IBM (and may ultimately replace it?).

One topic Ian has been researching through Dial-IBM is the avoidance of Control Region U0113 ABENDs, which occur when a DBCTL thread (CICS or BMP) suffers an ABEND, generally a Sx22, during a DL/1 call. The IMS Version 6 Guide (SG24-2228) also contains information on avoiding U0113s.

A trap can be implemented for S322 (CPU limit) and S522 (wait limit) – see the IEFUTL examples in Hints and Tips. For S322 the BMP should be cancelled using /STOP REGION xxx ABDUMP. For S522 investigation may be needed – e.g. if the problem is a PI wait then another region needs to be cancelled. S122/222 (Operator cancel) is prevented for BMPs in any case. S622 (TSO session cancel) is only a problem if you have BMP applications running under TSO, but should (almost) never happen as long as Parallel DL/1 is turned off.

This leaves CICS cancel. Ros McNeill said you should always cancel all the threads from DBCTL if possible before cancelling CICS. Dougie Lawson also recommended disconnection (using CDBC) as standard before CICS shutdown, maybe as a PLT process.

Any Other Business

The date, venue and format of the next meeting are to be decided – possibly Manchester in the spring?

The meeting closed at 4:20 p.m.

Address for IMS requirements / back-copies of minutes:

Neil Price
TNT Express Worldwide
Holly Lane
Atherstone
Warwicks CV9 2RY

Fax: 01827 710683 Email: Neil.Price@notes.tntew.com

List of attendees

Company

 Name

Barclays Bank Frank Fleming
CAP Gemini Chris Skaife
C.S.C. Anne Joyner
Ann Wareing
Federal Mogul I.T. Rosalind McNeill
IBM Dougie Lawson
Peter Sadler
Ian Tyson
ITT London & Edinburgh Insurance Dave Williams
Neon Systems Ed Jones
ORIGIN-IT Bram Dorreman
Mick Lofthouse
Trevor Wellings
TNT Express Worldwide Neil Price