23.3.1 SYSLOG

The system log (SYSLOG) is a data set residing in the primary job entry subsystem′s spool space. It can be used by application and system programmers to record communications about problem programs and system functions. The operator can use the LOG command to add an entry to the system log.

SYSLOG is queued for printing when the number of messages recorded reaches a threshold specified at system initialization. The operator can force the system log data set to be queued for printing before the threshold is reached by issuing the WRITELOG command. As part of the WRITELOG command, pick a SYSOUT class that is not used for normal printing so it is not printed unintentionally.

23.3.2 Printing SYSLOG

SYSLOG is so voluminous that you would not want to print the entire data set. Use SDSF to browse it and print portions by allocating SYSOUT data sets through JES.

Archive it using a spool archiving mechanism to save it for future problem determination and auditing purposes.

23.4 OPERLOG

The operations log (OPERLOG) is an MVS system logger application that records and merges messages about programs and system functions (the hardcopy message set) from each system in a sysplex that activates OPERLOG. Use OPERLOG rather than the system log (SYSLOG) as your hardcopy medium when you need a permanent log about operating conditions and maintenance for all systems in a sysplex. Only the systems in a sysplex that have specified and activated the operations log will have their records sent to OPERLOG.

The operations log is operationally independent of the system log. An installation can choose to run with either or both of the logs. If you choose to use the operations log as a replacement for SYSLOG, you can prevent the future use of SYSLOG; once the operations log is started with the SYSLOG not active, enter the WRITELOG CLOSE command.

In a single system environment, OPERLOG can reside on DASD, otherwise it is written to a coupling facility structure. When installation defined thresholds are reached, the system logger stores log data on DASD log data sets. You should use System Managed Storage (SMS) and DFHSM to manage the DASD log data sets. See OS/390 MVS Setting Up a Sysplex, GC28-1779 for details.

23.4.1 Printing OPERLOG

OPERLOG is so huge that you would not want to print the entire log stream. Use SDSF to browse it and print portions by allocating SYSOUT data sets for JES to print.

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IBM OS/390 manual Printing Syslog, Printing Operlog
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OS/390 specifications

IBM OS/390, a versatile operating system, was a cornerstone in enterprise environments and played a pivotal role in mainframe computing. Released in the mid-1990s, OS/390 combined the strengths of IBM's MVS (Multiple Virtual Storage) with new features and enhancements, targeting scalability, reliability, and performance in demanding business applications.

One of the key features of OS/390 was its robust support for multiple users and processes. The system allowed thousands of concurrent users to access applications and data, ensuring high availability and minimizing downtime—a critical requirement for many large organizations. This scalability was supported through various enhancements in memory management and processor scheduling, enabling optimal resource allocation across diverse workloads.

OS/390 was known for its superior workload management capabilities. The Workload Manager (WLM) component allowed administrators to define service policies, specifying how system resources would be allocated according to the priority of tasks. This ensured that critical business processes received the necessary resources while less critical tasks were managed more flexibly.

Another significant characteristic of OS/390 was its commitment to security. The operating system provided comprehensive security features, including user authentication, data encryption, and auditing capabilities. This focus on security was vital for organizations handling sensitive data, ensuring compliance with regulations and safeguarding against unauthorized access.

OS/390 also supported advanced technologies that facilitated integration and development. The system included features like the IBM CICS (Customer Information Control System) for transaction processing and IMS (Information Management System) for database management. These technologies allowed organizations to build robust, high-performance applications tailored to specific business needs.

The ease of network integration was another strength of OS/390. With the advent of the Internet and global connectivity, OS/390 systems could easily interface with various network protocols, enabling businesses to operate in a connected world. This inclusion paved the way for many organizations to expand their capabilities and offer new services, driving digital transformation.

In conclusion, IBM OS/390 represented a significant advancement in mainframe technology, combining scalability, security, and robust workload management. Its rich feature set and support for critical enterprise applications solidified its role as a vital component of many organizations' IT infrastructures, ensuring they could meet their operational challenges head-on while supporting future growth. As technology continues to evolve, the legacy of OS/390 remains influential in the realm of computing.
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