IBM Support



IBM held a Support Technical Exchange Open Mic session on the topic of VSAM Threadsafe support in CICS on 31 July 2008. This included a short introduction to the topic followed by a question and answer period in which a group of subject matter experts answered questions from customers.


Open Mic sessions are conducted in a question and answer format. The table below provides a time index (minutes:seconds) to the recording and describes the questions or topics discussed. You can fast forward to any question using the time index. A table containing the panel of experts is also included. This presentation was created at the CICS Transaction Server for z/OS (CICS TS) 3.2 level, but most of the information still applies; however things like offsets might have changed.

To play or download the 28 minute audio recording of this Open Mic session (MP3 files), see the Audio Section of this document.

Note that APAR PK45354 enabled file control threadsafety for local VSAM local shared resource (LSR) files in CICS Transaction Server for z/OS V3.2. PK45354 closed on 30 June 2008.

Open Mic session

Time Questions asked
00:00 Silence
00:30 General introduction
01:15 Technical introduction
05:35 What are the benefits of using VSAM Threadsafe? For example, can I expect significant improvements in CICS performance?
06:35 What type of effort does it take to switch over to VSAM Threadsafe? Is there a switch to turn it on and off in a CICS region in case I run into problems?
08:50 Is there anything special I need to know if I'm using file owning regions (FORs)? For example, will the CPU usage in the FORs increase?
10:55 Most of my files are accessed by function shipping to FORs. What gain will I see with the PTF for APAR PK45354?
11:20 The PTF for APAR PK45354 requires VSAM co-reqs.... What is the best way to roll the PTFs out across my regions and into production?
12:20 I am using RLS, how will APAR PK45354 affect me?
13:05 The latest APAR PK45354: File Control Threadsafety enabler for local VSAM LSR Files:

Is it true that Local VSAM + LSR + Storage Protection active = TCB Switch to QR (even after applying the mentioned APAR)?

This means for our installation that we cannot use FC Threadsafety with CICS TS V3.2 and z/OS V1.9 because we are using storage protection. If this is true what are the reasons for this behavior and is IBM planning to change this?
17:00 Remote files are not available when the phase 3 PLT is invoked in my FORs? Will APAR PK45354 have any affect on this?
20:05 An application program with execution key USER will not have to be switched to a QR TCB if storage protection is switched on or translation isolation is effective, is this true?
24:25 What anticipation do have for providing threadsafety for file control requests on FORs?
27:40 Closing remarks
28:05 End of Call

Panelist Title
Colin Penfold CICS Development
Martin Cocks CICS Development
Dai Middleton CICS Level3 Support
Ed Addison CICS Level2 Support
Maya Pandya VSAM Development


Click on Download Audio (MP3 format) to play the recording of this conference call. Right-click and select Save As to store the file on your local computer for later playback. Remember that you can fast forward to any question using the time index in this document.

Related information
IBM Redbooks: Threadsafe Considerations for CICS
Webcasts for CICS Transaction Server and OMEGAMON
Beta and Early Test Programs

Product Alias/Synonym

CICS/TS CICS TS CICS Transaction Server

Document information

More support for: CICS Transaction Server
File Control

Software version: 3.2, 4.1, 4.2, 5.1

Operating system(s): z/OS

Reference #: 7013082

Modified date: 2013-11-01