DTFPH Macro

Figure 54 shows the correspondence between the operands of the DTFPH macro and their MVS equivalents:

DTFPH OPERAND

MVS EQUIVALENT

 

 

TYPEFLE

OPEN macro

ASCII

OPTCD=Q

CCWADDR

Channel program address field of

DEVICE

IOB

DEVADDR

UNIT parameter of DD statement

LABADRR

UNIT parameter of DD statement

HDRINFO

EXLST parameter in DCB allows for

MOUNTED

label checking exits

XTNTXIT

No corresponding element

 

DD statement

 

DEB

 

 

Figure 54. Relationship between DTFPH Macro and MVS equivalents

You can also use the file name of the DTFPH file as the ddname of the corresponding MVS data set.

13.2.6.15 Comparison of Physical IOCS Elements

VSE Major Elements

MVS Major Elements

 

 

Define the file for physical IOCS (DTFPH)

Data Control Block (DCB) macro and

macro and control block

control block

 

 

TLBL statement

DD statement

 

 

DLBL statement

DD statement

 

 

EXTENT statement

DD statement

 

 

ASSGN statement

DD statement

 

 

OPEN macro

OPEN macro

 

 

XTNTXIT routine

Data Extent Block (DEB)

 

 

LABADDR routine

EXLST in Data Control Block (DCB)

 

 

Command Control Block (CCB)

Data Control Block (DCB)

macro and control block

Input/Output Block (IOB)

 

Event Control Block (ECB)

 

Data Extent Block (DEB)

 

 

EXCP macro

EXCP macro

 

 

WAIT macro

WAIT macro

 

 

CLOSE macro

CLOSE macro

 

 

FEOV macro

FEOV macro

 

 

SECTVAL macro

TRKCALC

 

 

SEOV macro

Not applicable

 

 

LBRET macro

RETURN macro

 

 

Figure 55. Comparison VSE and MVS Major Elements

328VSE to OS/390 Migration Workbook

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Image 352
IBM OS/390 manual Comparison of Physical Iocs Elements, Dtfph Macro

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.