Introduction

Many data processing installations have applications that contain time-sensitive logic—special processing that executes at certain intervals such as at the end of a week, month, or quarter. Until now, multiple system Power-On-Reset (POR) procedures were required to reset the MVS™ system clock to a test date and time, and then back to the current date and time. Setting the system clock in this manner affects not only the application being tested, but also other applications and components running on the system. Another drawback to the POR method is that only one test date and time can be in effect at a time.

HourGlass facilitates the testing of your time-sensitive applications by eliminating the POR procedures. Additionally, unlike the POR method, you may set as many altered date and time values as needed, and the altered values affect only the applications you specify. In other words, all other applications and system components such as your tape management system and system catalog are unaffected. With HourGlass, the testing of time-sensitive applications becomes simpler and less disruptive to your operation. So simple, in fact, that such testing becomes a normal day-to-day development activity.

Specifically, HourGlass allows you to temporarily alter the system date or time for one or more application programs to any date and time value supported by the MVS 64-bit time-of-day clock: 1900-01-01, 00:00:00.000000 (midnight) UTC through 2042-09-17, 23:53:47.370495 UTC.

The HourGlass product includes an Audit Trail Facility that aids in the identification of applications that request the system date and time. Audit trail reports display the frequency of requests, organized by job step, and show the date and time actually returned. The Audit Trail Facility can be used to track the job steps that must be tested for date or time compatibility. Later, it can be utilized to report on job steps making use of altered dates via the HourGlass product.

Incorporating HourGlass into your testing procedures can also help to ensure that your test environment is consistent regarding the dimension of time from one testing cycle to the next. This can make regression testing and the auditing of system changes easier and more reliable.

With HourGlass, you can adjust the time of day forward or backward from the current time by as much as 23 hours and 59 minutes. This facility can be used to run time-sensitive applications for users located in a time zone other than that of the data center in which the application runs. You can also simulate start times for specific processing steps as well as force the time to remain constant throughout the life of an application process.

Note: Setting date and time values in the past (that is, to a value prior to the current date and time), while extremely useful in a number of situations, may be undesirable at your site due to production control and auditing considerations. If your site prohibits the setting of date and time values in the past, contact Technical Support for a zap to implement this restriction.

HourGlass intercepts all system time-of-day requests that internally issue an SVC 11 instruction (equivalent to the TIME macro with the LINKAGE=SVC parameter) or requests to the PC Time and STCKSYNC system services (equivalent to the TIME macro with the LINKAGE=SYSTEM.parameter). These application-oriented interfaces are commonly used by most software products and programming languages to retrieve the date and time from the operating system.

A new HourGlass customization setting, STCKSYNC=Y|N, is provided in the AGGCUSTM program in the HourGlass SAGGSAMP library dataset. This setting can be used to control enablement or disablement of the HourGlass STCKSYNC support feature. The default setting is STCKSYNC=N. The AGGOPTS program (Options List Utility) has been enhanced to display the status of the STCKSYNC customization setting. The AGGVRFY program (install verification job) has been expanded to provide verification for the HourGlass STCKSYNC support feature. The results of both a 64-bit (STCK) STCKSYNC and a 128-bit (STCKE) STCKSYNC* time request are displayed. Modifications have been made to the AGGLSPC program (TIME LINKAGE=SYSTEM Support) to recognize and handle time requests originating from the MVS STCKSYNC service.

Note: This change only addresses the date and time value returned from the STCKSYNC service request that may be modified by HourGlass. The ETRID value and the CTNID value returned from the STCKSYNC service request are not modified by HourGlass in any way.

HourGlass does not automatically intercept time-of-day requests made via the Store Clock (STCK) instruction since the STCK instruction is purely a hardware function. Nevertheless, HourGlass is able to intercept time-of-day requests when made from one of the several products that normally use the STCK instruction, for which a product-specific interface has been developed. Such interfaces are available for several products including DB2, Enterprise Cobol for z/OS®, Enterprise PL/I for z/OS, and others. For other products containing the STCK instruction for which you have the source, you can reassemble the module using a supplied STCK macro. If the module source is not available, or a module reassembly is undesirable, the STCK instructions in the load module can be patched to allow interception and processing by HourGlass.

HourGlass can be used in both the batch and online environments. Full support for IMS message regions (online IMS) and CICS regions is provided. In an IMS online environment, all transactions running in a message region or group of message regions can receive an altered date and time value that is common to all transactions in the region or group. This is called region-level or global-level control.

Alternatively, individual users can override the region-level date and time value and receive a date and time value unique to their userid. This is called user-level control. Both global-level and user-level control are supported as well in the CICS Transaction Server product, and DC COBOL environments.

In the IMS online environment, HourGlass does not provide support for altering the MFS date keywords, but does provide support for setting the HourGlass-altered date and time value in the IMS IOPCB. See the HourGlass SAGGSAMP library member IMSIOPCB for further information.

In the DB2 environment, HourGlass provides altered date and time values for time requests made via the DB2 special registers CURRENT DATE, CURRENT TIME and CURRENT TIMESTAMP as well as for inserts of DATE, TIME, or TIMESTAMP columns for which no value is specified, and are defined with the NOT NULL WITH DEFAULT attribute.