7.3 Executing Programs at a Terminal

Both ICCF, TSO/E, and ISPF provide commands to compile, link-edit, and execute (or compile and load) your source program at the terminal. They also allow you to use other programs, such as utilities at the terminal.

Under ICCF programs that expect input from the console will read input from your terminal. Card input is either entered from the terminal (/DATA INCON) when requested from SYSIPT or SYS005 or can be included from an ICCF library member (/DATA NOINCON followed by /INCLUDE). List output will be returned to your terminal.

Under TSO/E, you define your input and output data sets via the ALLOCATE subcommand of the EDIT command, or the ALLOCATE command. You may allocate a data set to the terminal by using an asterisk (*) as the data set name. The following example shows the use of the ALLOCATE command for allocating the data sets required for an execution of the Assembler.

.

.

READY

allocate dataset(′ sys1.maclib′) file(syslib) shr

READY

allocate file(sysut1) new block(400) space(400,50)

READY

allocate file(sysut2) new block(400) space(400,50)

READY

allocate file(sysut3) new block(400) space(400,50)

READY

allocate dataset(*) file(sysprint)

READY

allocate file(syspunch) sysout

READY

allocate dataset(prog.obj) file(sysgo) new block(80) space(200,50)

READY

allocate dataset(input.asm) file(sysin) old

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.

The ALLOCATE commands in the example would define the macro library to be used by the assembler (SYSLIB), the assembler work data sets (SYSUT1, SYSUT2, and SYSUT3), a data set for the punched deck of an object module (SYSPUNCH), a data set for the link and go object deck (SYSGO), the input to the assembler (SYSIN) which is a data set with the fully qualified name

userid.INPUT.ASM′, and the output of the assembler (SYSPRINT) which is to be directed back to the terminal.

Note that rather than using the commands shown above, your users will probably wish to use ISPFs facilities for invoking the assembler or compilers. These facilities, commonly available from option 4 of the main ISPF panel, automate much of the work of invoking compilers, assemblers and so on.

If you have to allocate the same data sets every time you log on, you can have your installation allocate them in the form of fully defined data sets in the LOGON procedure or you can build a command procedure containing your ALLOCATE commands and execute that procedure as soon as you are logged on.

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IBM OS/390 manual Executing Programs at a Terminal, Ready

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.