MVS Programming: Authorized Assembler Services Guide

- Abstract for MVS Programming: Authorized Assembler Services Guide
- Summary of changes
Introduction
Subtask creation and control
- Creating a new task (ATTACH or ATTACHX macro)
- Ensuring that a process completes (STATUS macro)
- Communicating with a program (EXTRACT, QEDIT)
  - Providing an EXTRACT answer area
Program management
- Residency and addressing mode of programs
  - Placement of modules in storage
  - Addressing mode
- Specifying where the module is to be loaded (LOAD macro)
- Synchronous exits (SYNCH or SYNCHX macro)
- Using checkpoint/restart
- Using re-entrant modules
- Using LLACOPY to refresh LLA directories
- Changing the LNKLST concatenation
  - Changing the current LNKLST set
- Monitoring dynamic LPA processing
  - Listing contents of dynamic LPA with CSVDLPAU
    - Invoking CSVDLPAU
      - CSVD002W
Serialization
- Choosing a serialization service
- Providing ENQ resource information on DISPLAY GRS command
- Locking
- Using the must-complete function (ENQ/DEQ)
  - Characteristics of the must-complete function
  - Programming notes
- Shared direct access storage devices (shared DASD)
- Serializing parallel tasks (WAIT and POST)
- Writing POST exit routines
- Branch entry to the POST service routine
- Branch entry to the WAIT service routine
- Serializing RB processing
- Synchronizing unit of work (tasks or SRBs)
- Global resource serialization latch manager
  - Overview
  - How to use the callable services
- Planning to use the latch manager callable services
- Guide to the latch manager callable services
Reporting system characteristics
- Collecting information about resources and their requestors (ISGQUERY and GQSCAN macros)
  - How GQSCAN returns resource information
    - How area size determines the information GQSCAN returns
    - How scope and token values determine the information GQSCAN returns
  - How global resource serialization determines the scope of an ENQ or RESERVE request
- Using the SRM reporting interface to measure subsystem activity
- Obtaining dispatchability data about address spaces (IEAMRMF3 macro)
Tracing applications using component trace
- Planning an application trace
- Coding macros for application traces
- Coding a start/stop exit routine
- Coding a display trace exit routine
- Creating trace entries
  - Understanding the fields in a CTE
  - Organizing variable data in CTEs
Communication
- Interprocessor communication
- Writing and Deleting Messages (WTO, WTOR, and DOM Macros)
- Issuing an internal START or REPLY command (MGCR)
- Issuing operator commands from a program (MGCRE macro)
- Issuing a command response message
- Controlling command flooding (IEECMDS macro)
- Routing commands in a sysplex (CPF macro)
  - Assigning a prefix
  - Persistence of the prefix
- What is an extended MCS console?
Listening for system events
- Establishing a listen request
  - Qualifying events
    - QUAL example
  - nn filtering events
- Coding the listener user exit routine
  - Non-SRBEXIT routine
  - SRBEXIT routine
- Passing parameters to a listener user exit routine
- Ending the listener user exit routine
- ENF event codes and meanings
- ENF sample programs
  - SMFLSTEN - Sample ENF listener
- Listening for global resource serialization-related system events
  - Monitoring contention changes
    - Listening for RNL change data
    - Listening for other global resource serialization events
Using a service request block (SRB)
- What is an SRB?
- Why would you use an SRB?
- Scheduling and managing SRBs
- Specifying the addressing environment of the SRB routine
  - Using the ENV parameter on IEAMSCHD
  - Using the MODE parameter on SCHEDULE
- Characteristics and restrictions of SRB routines
  - Implications of running in SRB mode
  - Environment of the SRB routine at entry
- Scheduling an SRB (IEAMSCHD or SCHEDULE macro)
  - Scheduling an SRB using IEAMSCHD
  - Scheduling an SRB using SCHEDULE
    - Initializing the SRB
- Purging an SRB (PURGEDQ macro)
- Serializing SRB processing
- Terminating a preemptable SRB
- Calling an SRB to run synchronously
- Transferring control for SRB processing (TCTL macro)
Virtual storage management
- Allocating and freeing virtual storage (GETMAIN, FREEMAIN and STORAGE macros)
- Using cell pool services (CPOOL macro)
- Selecting the right subpool for your virtual storage request
  - Program authorization
- Tracking virtual storage allocation (CPOOL BUILD, GETMAIN, and STORAGE OBTAIN macros)
- Obtaining information about the allocation of virtual storage (VSMLIST)
  - Using the VSMLIST work area
- Using IARQD — The page status interface routine
Accessing the scheduler work area
- Using the IEFQMREQ and the SWAREQ macros
The virtual lookaside facility (VLF)
- Deciding when to use VLF
- Planning to use VLF
- Using the VLF macros
Data-in-virtual
- When to use data-in-virtual
  - Factors affecting performance
  - Creating a linear data set
- Using the services of data-in-virtual
  - Identify
  - Access
  - Map
  - Save, Savelist, and Reset
  - Unmap
  - Unaccess
  - Unidentify
- The IDENTIFY service
- The ACCESS service
- The MAP service
- The SAVE service
- The SAVELIST service
- The RESET service
  - Effect of RETAIN mode on RESET
- The UNACCESS and UNIDENTIFY services
- Sharing data in an object
- DIV macro programming examples
  - Executing an application
  - Processing a data-in-virtual object
Sharing application data (name/token callable services)
- Levels for name/token pairs
  - Determining what your program can do with name/token pairs
- Checking authorization when retrieving a token
- Deciding what name/token level you need
  - Primary-level name/token pair
  - System-level name/token pair
- Owning and deleting name/token pairs
  - Example of using the name/token services
Processor storage management
- Fixing/freeing virtual storage contents
- Protecting a range of virtual storage pages
- PGFIX/PGFREE completion considerations
- Input to page services
- Branch entry to page services
  - Cross memory mode
  - Non-cross memory mode
Sharing data in virtual storage (IARVSERV macro)
- Understanding the concepts of sharing data with IARVSERV
- Storage you can use with IARVSERV
- Obtaining storage for the source and target
- Defining storage for sharing data and access
- Changing storage access
- How to share and unshare data
- Accessing data in a sharing group
- Example of sharing storage with IARVSERV
- Use with data-in-virtual (DIV macro)
- Use with page services (PGSER macro)
- Diagnosing problems with shared data
- Converting a central to virtual storage address (IARR2V macro)
The nucleus
- Linking to routines in the DAT-OFF nucleus (DATOFF)
- Obtaining information about CSECTs in the DAT-ON nucleus (NUCLKUP)
- Customizing the nucleus region
  - The NMLDEF macro
  - Removing existing routines from IEANUC0x
Providing recovery
- Understanding general recovery concepts
- Writing recovery routines
- Understanding the recovery environment
  - Register contents
  - Other environmental factors in recovery
- Understanding recovery through a coded example
- Understanding advanced recovery topics
- Using STAE/STAI routines
Processing program interruptions (SPIE, ESPIE)
- Interruption types
Dumping virtual storage (SDUMPX, SDUMP, and IEATDUMP macros)
- SVC dumps
- Transaction dumps
Protecting the system
- System integrity
- Authorized programs
- Using APF to restrict access to system functions
- Resource Access Control Facility (RACF)
- System Authorization Facility (SAF)
- Using the command authorization service
  - Command resource names
    - Syntax
    - Examples
- Changing system status (MODESET)
  - Generating an SVC
  - Generating inline code
Exit routines
- Using asynchronous exit routines
- Establishing a timer disabled interrupt exit
  - DIE characteristics
    - Exit from the DIE routine
    - DIE execution
  - Timer queue element control
- Using dynamic exits services
User-written SVC routines
- Writing SVC routines
- Inserting SVC routines into the control program
  - Standard SVC routines
  - Extended SVC routines
- Subsystem SVC screening
Accessing unit control blocks (UCBs)
- Scanning for UCBs
- Obtaining UCB addresses
- Ensuring that UCBs are not deleted
- Requesting notification of I/O configuration changes
- Detecting I/O configuration changes
- Retrieving the current MIH time interval
- Retrieving information about I/O hardware on an I/O path
- Validating I/O paths
- Obtaining device information for an allocation request
- Configuring a channel path online or offline
- Obtaining UCB information (general methods)
- Obtaining UCB information (limited method)
- Accessing above 16-megabyte UCBs
Dynamic allocation
- An allocation overview
- Dynamic allocation functions
- Installation options for DYNALLOC macro functions
Requesting dynamic allocation functions
- Building the SVC 99 parameter list
- Processing messages and reason codes from dynamic allocation
  - Setting up the request block extension
    - S99RBX fields
  - Processing messages from dynamic allocation
- Interpreting DYNALLOC return codes
  - Interpreting information reason codes from DYNALLOC
  - Interpreting error reason codes from DYNALLOC
- SVC 99 parameter list verb codes and text units, by function
- Example of a Dynamic Allocation Request
Dynamic output
- Creating and naming output descriptors
Scheduler JCL facility (SJF)
- Understanding SJF terms
- Understanding the OUTDES statement
Processing user trace entries in the system trace table
- Formatting a USRn trace table entry
- Replacing a USRn TTE formatting routine
Using system logger services
- What is system logger?
  - The log stream
    - Coupling facility log stream
    - DASD-only log stream
- The system logger configuration
  - The system logger component
- Overview of authorized system logger services
- IXGCONN: Connecting to and disconnecting from a log stream
- IXGDELET: Deleting log blocks from a log stream
  - Delete requests and resource manager exit processing
- Setting up the system logger configuration
  - Writing an ENF event 48 listen exit
- Logger server address space availability considerations
- When things go wrong: Recovery scenarios for system logger
  - When a resource manager fails
System REXX
- Planning to use system REXX
- Security
- Argument and variable processing
- Input/output files
- Functions
- Time limits and canceling a request
- Error handling
- Examples
z/OS FBA services
- z/OS Distributed Data Backup (zDDB)
- z/OS FBA devices
  - Controlling access to z/OS FBA devices
- z/OS FBA services
Using the unit verification service
- Functions