Executing a DSP or Installation Exit Routine in a C/I FSS Address Space

If your installation uses C/I functional subsystem (FSS) address spaces, any installation exit routine that executes during the converter, interpreter, and prescan phases of C/I processing must be able to execute in a C/I FSS address space environment. Any DSP you write that executes in a C/I FSS address space must also be compatible with the C/I FSS address space environment. The C/I FSS address space contains only a subset of the nucleus modules and services that are available in the JES3 address space.

When writing an installation exit routine or DSP to execute in a C/I FSS address space, apply the same rules and procedures as those explained in section Programming Conventions for Writing DSPs and Installation Exits. However, be sure that the routine or DSP uses only those services that are available in a C/I FSS address space.

The following installation exit routines can execute in a C/I FSS address space:

&tab;IATUX03&tab;IATUX09
&tab;IATUX04&tab;IATUX10
&tab;IATUX05&tab;IATUX41
&tab;IATUX06

Table 1 shows which macros are available in a C/I address space.

Table 1. JES3 Executable Macros Available in a C/I FSS Address Space
Dump Formatting Macro Instructions
ABNCODE ABNCVDEC ABNCVHEX	ABNGET ABNPUT	ABNVRFY IATXMGET
Spool Data Management Macro Instructions
ABACKR ABLOCK ACLOSE ADEBLOCK AGETBUF ALOCATE ANOTE	AOPEN AOPEND APOINT APUTBUF ARELEASE ATRACK AWRITE	IATXCPYF IATXIOX IATXRDCH IATXRELC IATXSAS IATXSIO IATXUBAL JESREAD WRTCHAIN
JES3 Checkpoint Macro Instructions
IATXCKPT
DSP Program Management Macro Instructions
ACALL ADELETE ALOAD ARETURN FAILDSP IATXATF	IATXCSF IATXFRQ IATXGENF IATXGFC IATXGRQ IATXICA	JESTAE RQTAADD RQTADEL RQTAPUT VIOLATE
Resource Control Macro Instructions
ADEQ AENQ	ATEST	AWAIT
Storage Management Macro Instructions
AGETMAIN APUTMAIN IATXBFM	IATXBGM IATXBPL IATXDPL	IATXGCL IATXRCL IATXSQE
Communication Macro Instructions
CONCNVRT CONREVRT IATXCNS IATXIWT IATXMID	IATXSCN1 IATXSCN2 JESMSG JSERV	LOGIN LOGOUT MESSAGE SSISERV
Job Management Macro Instructions
IATXELA IATXELD IATXELS IATXRABC	IATXRABP JDSADD JDSGET JDSHOLD	JDSPOINT JDSPUT JDSREL
JES3 Initialization Macro Instructions
ICONVBIN ICONVHEX INITMWLE	ISCAN1 ISCAN2 ISORT	ITREAD IWASPOUT
SNA RJP Macro Instructions
IATXDEQ	IATXENQ
JES3 Inner Macro Instructions
IATXTREG IATZCALL IATZLOAD	IATZMEXC IATZMNOT IATZMOVE	IATZPCHK IATZTYPE RQTAGEN
Miscellaneous Macro Instructions
ACVX ATIME IATXCUE IATXCVB IATXCVD IATXDYH	IATXDYT IATXLPJ3 IATXMPC IATXPHEX IATXPRT IATXPTCH	IATXTOD IATXTRC MOVEDATA MTBL ZEROCORE
Note: Macros issued by a routine that runs in a C/I FSS address space must not allocate track groups from the single track table (STT). Only routines operating in the JES3 global address space can access the STT.

The following other services are available in a C/I FSS address space:

JES3 ESTAE and ESTAE retry routines
The generalized subtask (macro IATXCSF)
DIE and termination routines
The initialization driver (module IATINIT)
The JSAM DSP (resident FCT)
The track allocation DSP (resident FCT)
The FSS driver DSP (resident FCT)
The general services DSP (resident FCT)
The FAILSOFT DSP (resident FCT)
The WAIT DSP (resident FCT)
The ABEND formatting routines
The CI DSP (converter/interpreter and prescan phases only)
The IOERR DSP
The FSS DSP dictionary (module IATGRPTF)
The FSS TVT (module IATGRVTF)
Any services accessible from a user address space.

Each C/I FSS address space has its own trace table and storage queue (not shared by the JES3 address space) in private area virtual storage.

For a complete list of all modules contained in the C/I FSS address space nucleus (IATNUCF), see z/OS JES3 Diagnosis Reference.

Installation exits and DSPs executing in C/I FSS address spaces may update a job's spool files using JSAM or USAM. JSAM should be used when running under an FCT. USAM should be used when running under a subtask. To serialize access to the spool files, most of the job's control blocks are “locked” in the JES3 global address space before the job is sent to the C/I FSS address space. (Control blocks are locked by turning off the FDBCLOSE bit in the appropriate FDB in the job's RQ.) Routines in the C/I FSS address space can then update the job's spool files while routines in the JES3 global address space cannot.

The only control block that is not “locked” is the job track allocation table (TAT). Job TAT updating for a DSP or installation exit routine executing in a C/I FSS address space must be done only from the JES3 global address space. To ensure proper spool space allocation, use the ATRACK macro, which sends the allocation request to the JES3 global address space. Failure to do so could cause duplicate track allocation and may force a cold start.