In TechTalk, February 1994, MC published a technique that determines if a subsystem is inactive. If the subsystem is inactive when the Work Subsystem Job (WRKSBSJOB) command is executed against it, a certain CPF message is returned. I found this technique to be inefficient. If the subsystem is active, this method takes too long to complete, and it creates a useless spool file that has to be manually deleted.

I found a faster, more efficient way to determine the status of a subsystem. I created a command called Check Subsystem Status (CHKSBSSTS) that uses an IBM-supplied API, QWDRSBSD, to retrieve the status of a subsystem.

The command input is the qualified name of the subsystem description for which you want the status. The command output is the STATUS parameter. The STATUS parameter returns one of three values: Y if the subsystem is active, N if the subsystem is inactive, and ? if the subsystem description isn't found. Since the command returns a value, it can only be allowed to run in a CL program or *REXX procedure. 12 shows the compile instructions and the CHKSBSSTS command source code.

The command input is the qualified name of the subsystem description for which you want the status. The command output is the STATUS parameter. The STATUS parameter returns one of three values: Y if the subsystem is active, N if the subsystem is inactive, and ? if the subsystem description isn't found. Since the command returns a value, it can only be allowed to run in a CL program or *REXX procedure. Figure 12 shows the compile instructions and the CHKSBSSTS command source code.

The command processing program (CPP) for CHKSBSSTS is RPG program SBS001RG (see 13). Here, I'm using the QWDRSBSD API to retrieve the status of the subsystem. However, you can retrieve much more information about subsystem descriptions through this API. See the OS/400 System API Reference V3R1 manual (SC41-3801, CD-ROM QBKAVD00) for more information.

The command processing program (CPP) for CHKSBSSTS is RPG program SBS001RG (see Figure 13). Here, I'm using the QWDRSBSD API to retrieve the status of the subsystem. However, you can retrieve much more information about subsystem descriptions through this API. See the OS/400 System API Reference V3R1 manual (SC41-3801, CD-ROM QBKAVD00) for more information.

? Robert T. Fisher

TechTalk: Is the Subsystem Active?

Figure 12: CHKSBSSTS Command Source

 /*==================================================================*/ /* To compile: */ /* */ /* CRTCMD CMD(XXX/CHKSBSSTS) PGM(XXX/SBS001CL) + */ /* SRCFILE(XXX/QCMDSRC) ALLOW(*IPGM *BPGM + */ /* *IREXX *BREXX *IMOD *BMOD) */ /* */ /* Returns a value in STATUS parameter: */ /* 'Y' = Subsystem active */ /* 'N' = Subsystem inactive */ /* '?' = Subsyste description not found */ /* */ /*==================================================================*/ CHKSBSSTS: CMD PROMPT('Check Subsystem Status') PARM KWD(SBSD) TYPE(QUAL1) MIN(1) + PROMPT('Subsystem description') QUAL1: QUAL TYPE(*NAME) LEN(10) QUAL TYPE(*NAME) LEN(10) DFT(*LIBL) SPCVAL(*LIBL) + PROMPT('Library name') PARM KWD(STATUS) TYPE(*CHAR) LEN(1) RTNVAL(*YES) + PROMPT('Subsystem status (A, I, ?)') 
 
TechTalk: Is the Subsystem Active?
 
Figure 13: Command Processing Program SBS001RG
 
 *=============================================================== * To compile: * * CRTRPGPGM PGM(XXX/SBS001RG) SRCFILE(XXX/QRPGSRC) * *=============================================================== *. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 I IDS I B 1 40LEN I B 5 80ERRCOD I DS I@SBSI DS I 29 38 STATUS I '*ACTIVE' C $ACT I '*INACTIVE' C $INACT * C *ENTRY PLIST C PARM @SBSD 20 C PARM ACT 1 * C MOVE @SBSD LIB 10 * C LIB IFEQ *BLANKS C MOVEL'*LIBL' LIB P C ENDIF * C CALL 'QWDRSBSD' 99 C PARM @SBSI C PARM 38 LEN C PARM 'SBSI0100'FORMAT 8 C PARM @SBSD C PARM ERRCOD * C STATUS IFEQ $ACT C MOVE 'Y' ACT C ELSE C STATUS IFEQ $INACT C MOVE 'N' ACT C ELSE C MOVE '?' ACT C ENDIF C ENDIF C MOVE *ON *INLR *. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7