AR/CTL data services
Data services focus on reestablishing the application program’s position within data structures at restart. Data services also provide availability, integrity, and performance enhancements for supported data structures.
Depending on the type of application program and the AR/CTL products you have, AR/CTL provides the following data services:
Sequential (QSAM) file interception
AR/CTL provides sequential file interception for data sets that an application program accesses through standard z/OS queued sequential access method (QSAM) I/O requests. AR/CTL dynamically intercepts these requests so that it can reposition the data set at restart time.
Local VSAM access
AR/CTL provides local VSAM access for VSAM data sets accessed exclusively by a batch VSAM application program. The program issues native VSAM requests. AR/CTL for VSAM dynamically intercepts these requests to provide repositioning support. AR/CTL can also provide logging and dynamic backout of uncommitted changes made by the batch program.
Remote VSAM access (file sharing)
AR/CTL provides remote VSAM access (also known as VSAM file sharing) to allow VSAM data sets to be shared and updated between a batch VSAM application program and one or more IBM CICS regions. The batch program and the CICS regions can execute on a single z/OS image or on different z/OS images within a SYSPLEX environment. While a file is being shared, the CICS region owns the data sets; it manages all access to the data sets, logs changes made by those transactions, and backs out uncommitted changes in case of failure. AR/CTL dynamically intercepts the native VSAM requests issued by a batch VSAM application program, transforms the requests to online CICS commands, and ships the commands to the CICS region for service.
IMS GSAM replacement
AR/CTL can replace IMS generalized sequential access method (GSAM) services with enhanced AR/CTL services. GSAM replacement is for IMS and IMS compatible application programs.
ASAM callable interface
AR/CTL provides the application sequential access method (ASAM) callable interface mainly for Db2 application programs to use if AR/CTL for VSAM is not available. A program can use the ASAM callable interface to obtain limited support for repositioning of VSAM entry-sequenced data sets (ESDSs), input VSAM key-sequenced data sets (KSDSs), and standard z/OS sequential files.
QUICKSTART-to-AR/CTL bridge
AR/CTL provides the QUICKSTART for MVS-to-AR/CTL bridge, which allows AR/CTL to support (without program changes in most cases) application programs that use the QUICKSTART for MVS product.
Automatic Db2 cursor repositioning
AR/CTL can perform repositioning automatically for the Db2 cursors used by an application program. After an abend, cursor position (the point where the application program was processing) is lost. At restart, AR/CTL can reestablish the cursor position at the last completed checkpoint.
If an application program is modified between cold start and restart, then AR/CTL requires both cold start and restart versions of the Db2 package. Both versions of the Db2 package must be in the Db2 catalog for automatic Db2 cursor repositioning to work correctly.
Program exception handling
AR/CTL can handle certain program exception errors automatically. If an error that would cause a system 0Cx-type abend occurs, AR/CTL can ignore the error and continue, ignore the bad record and reattach the application program task, or write the bad record to a file and reattach the task.
SQL return code handling
AR/CTL can intercept a defined SQL return code and transform it to a user abend code that can then be defined as eligible for application reattach processing.
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