Using DFSMSdfp Callable Services

This information describes the DFSMSdfp-related callable services. Callable services reside in SYS1.CSSLIB, the callable system service library. They are invoked from a user program by issuing a CALL statement, accompanied by a parameter identifying the desired service and a list of service-specific arguments and storage areas. The intent is that if you link edit any of the routines described here with your program, the routine continues to execute correctly on future levels of the operating system.

The DFSMSdfp callable services provide 15 callable system services. They can be invoked by the high-level languages supported by z/OS Language Environment® and by assembler language callers.

Note: Nine of these callable services are related to using the character data representation architecture (CDRA) identifiers.They are application program interfaces (APIs) that are needed to consistently and correctly process graphic character data. We have listed them here (see Character Data Representation Architecture (CDRA) APIs), but for detailed information on their use, refer to Character Data Representation Architecture Reference and Registry Character Data Representation Architecture Reference and Registry Character Data Representation Architecture Reference and Registry.

These services enable programs written in assembler language or high-level languages to use:

IECTRKAD to perform conversions and compares of DASD track addresses that contain 16-bit or 28-bit cylinder numbers.
IGWARLS to query the information in the catalog for record-level sharing (RLS), including the values of the LOG, BWO, and LOGSTREAMID parameters, the VSAM_QUIESCED indicator, the RLS_RECOVERY_TIMESTAMP fields, and whether the sphere requires forward recovery.
IGWABWO to communicate with DFSMSdfp to retrieve or set various data set–related indicators. Through the use of these indicators, your program can determine if a data set is eligible for backup while it is open for update and, if eligible, what action can or should be taken. See Table 1 for an explanation of the indicators.
IGWASMS to return certain data set attributes for SMS managed data sets. These data set attributes are:
- SMSDATA—SMS class names, that is, storage class, management class, and data class.
- DSTYPE—Currently indicates whether the data set is a PDSE-type data set, HFS, or neither.
  Note: If IGWASMS is called for a non-SMS managed data set, zeros are returned for the DSTYPE attribute.
IGWASYS to determine the version, release, and modification level of DFSMSdfp on your system, and the status of the SMS subsystem.
IGWLSHR to determine the DFSMSdfp share attributes in use on the current system.

This information describes calling the service from a nonreentrant program written in assembler language. See z/OS MVS Programming: Assembler Services Reference ABE-HSP for information on using CALL in a reentrant program. For information on using CALL in programs written in high-level languages, see the applicable language documentation.

Your program can call the DFSMSdfp callable services in either 24- or 31-bit AMODE. The program can be executed in any protection key and in either supervisor or problem state. When you invoke any of the callable services, your program must provide the address of a standard 18 word save area in register 13. The syntax diagrams here show a CALL statement in assembler language. These callable services can be invoked in the following two ways:

A CALL statement is coded in the invoking application. The callable services IGWASYS, IGWASMS, IGWABWO, IGWLSHR or IGWARLS, among others, are in SYS1.CSSLIB. When link-editing the invoking application, specify SYS1.CSSLIB in the library concatenation.
The invoking application can issue a LINK or LOAD/CALL to the desired service, IGWASYS, IGWASMS, IGWABWO, IGWLSHR, or IGWARLS. For an example of using a LINK macro, see Example. For an example of using CALL and LOAD/CALL macros, see Example and Example.
To invoke the callable services write a set of arguments in a specific order on the invocation. The number of arguments associated with each callable service is fixed, and the types of arguments are restricted to 32-bit binary integers (hereafter referred to as integers) and fixed-length EBCDIC character strings. The CALL statement format is described in the following information: