How to Add a Command or EXEC Procedure to eMS You can create a module or EXEC procedure that executes in the user area and resides on disk. In order to execute such a co •• and or EXEC procedure, you only have to enter the filename from the terminal.
However, be aWare of the CKS search order for terminal input. Once a match is found, the search stops. The search order is:
1. EXEC file on any currently accessed disk.
2. Valid abbreviation for an EXEC file on any currently accessed disk.
3. Nucleus-resident or transient area coamand.
4. Command on any currently accessed disk.
5. Valid abbreviation or synonym for nucleus resident or transient
area command.
6. Valid abbreviation for disk-resident co •• and.
For example, if you create an EXEC file with the same name as a disk
resident command, the CKS search will always find the EXEC file first.
Thus, the disk resident command will never get executed. CKS has a function table containing the names of CftS functions. CftS reserves the following na.es, all entries in the CftS FUNCTAB (found in DKSFNC), for its own use:
ATTN CARDPH CARDRD CKSTIKE CONREAD CONiAIT CP DEBUG DESBUF DKSCIOSI DKSERR DKSLADAD DKSPIOCC DKSPIOSI DftSSKNAT DKSVSR ERASE EXEC FETCH FINIS GENKOD INCLUDE LOAD LOADKOD POINT PRINTIO PRINTR RDBUF RETURN START STATE STATEW SUBSET SVCFREE SVCFRET TIPEIO TRAP TYPLIN WAIT WIITRD iRBUF Part 3. Conversational Konitor syste. (CftS) 269
OS Macro Simulation under eMS When a language processor or a user-written program is executing in the CMS environment and using OS-type functions, it is not executing os
code. Instead, CMS provides routines that simulate the as functions
required to support as language processors and their generated object
code. CMS functionally simulates the as macros in a way that presents
equivalent results to programs executing under eMS. The as macros are
supported only to the extent stated in the publications for the sUFPorted language processors, and then only to the extent necessary to
successfully satisfy the specific requirement of the supervisory
function.
The restrictions for COBOL and PL/I program execution listed in
"Executing a Program that Uses as Macros" in the glanning Qene!g!i2n exist because of the limited CMS simulation of
the as macros.
Figure 31 shows the as macro functions that are partially or
completely simulated, as defined by SVC number. OS Data Management Simulation The disk format and data base organization of CMS are different fre.
those of as. A CMS file produced by an as program running under CMS and
written on a CMS disk, has a different format from that of an as data
set produced by the same as program running under as and written on an OS disk. The data is exactly the same, but its format is different. (An
as disk is one that has been formatted by an as program, such as IBCDASDI. ) HANDLING FILES THAT RESIDE ON CMS DISKS CMS can read, write, or update any as data that resides on a CMS disk.
By simulating as macros, CMS si.ulates the following access methods so
that as data organized by these access methods can reside on CMS disks:
direct
partitioned
sequential
identifying a record by a key or by its relative
position within the data set.
seeking a named member within the data set.
accessing a record in a sequence in relation to
preceding or following items in the data set.
Refer to Figure 31 and the "Simulation Notes," then read "Access Method Support" to see how CMS handles these access methods. Since CMS does not simulate the indexed sequential access method (ISAM), no as program that uses ISAM can execute under eMS. Therefore,
no program can write an indexed sequential data set on a CMS disk. 270 IBM VM/370 System Programmer's Guide
Previous Page Next Page