24
Sun, Nov
1 New Articles

TechTalk: Save and Restore Library List

General
Typography
  • Smaller Small Medium Big Bigger
  • Default Helvetica Segoe Georgia Times

Much has been written about the library list; it's a topic that confuses enough people to deserve repeated treatment and explanations. For instance, one of the questions in everyone's mind is "How can I make sure the library list returns to its original setup after I've changed it?"

The ideal solution is to store the library list in some kind of object so that it can be retrieved later from the same object. Data areas come to mind as the repositories for library lists, except that you have to give them names, even if placed in QTEMP. So far, the best solution I've found is to use not data areas, but data queues. This approach made me write two utility commands: Save Library List (SAVLIBL) and Restore Library List (RSTLIBL).

SAVLIBL (Figure 6) uses a LIFO data queue named LIBLSTACK in QTEMP, which is created if nonexistent. Its processing program, LIBL007CL (Figure 7) takes care of everything. It retrieves the user portion of the library list, as well as the current library name, and calls QSNDDTAQ to write that information into the data queue. The first 10 characters of the entry contain the current library name, and the next 275 characters contain the user portion of the library list, in 25 eleven-byte buckets.

RSTLIBL (Figure 8) performs the opposite function: It retrieves the last entry in the data queue and changes the library list accordingly. For that, its processing program (LIBL008CL, in Figure
9) calls QRCVDTAQ, runs the Change Current Library (CHGCURLIB) command, and builds a Change Library List (CHGLIBL) command in a CL variable, which is then executed via a call to QCMDEXC.

Figure 10 shows how you can use these two commands. If you're going to run a program that needs to change the library list, code a SAVLIBL before any changes. Then, do whatever you need to do and code a RSTLIBL at the end. Because SAVLIBL and RSTLIBL use a LIFO data queue, your program may call another program, which, in turn, uses SAVLIBL and RSTLIBL. This means that SAVLIBL and RSTLIBL provide you with an unlimited number of "versions" of the library list-and you don't need to bother naming them!

SAVLIBL is smart enough to create the necessary data queue if it doesn't find it (as would be the case the first time SAVLIBL runs in a job). RSTLIBL ends with an escape message (CPF9898) if the data queue does not exist (i.e., if SAVLIBL has never run in the current job) or is empty
(i.e., if there is no corresponding SAVLIBL to the RSTLIBL you're running now). SAVLIBL and RSTLIBL must always go in pairs.

- Ernie Malaga

Figure 6: The SAVLIBL command

/*===================================================================*/

/* To compile: */
/* */
/* CRTCMD CMD(XXX/SAVLIBL) PGM(XXX/LIBL007CL) + */
/* SRCFILE(XXX/SOURCE) TEXT('Save Library List*/
/* */
/*===================================================================*/

CMD PROMPT('Save Library List') /*===================================================================*/

/* To compile: */
/* */
/* CRTCLPGM PGM(XXX/LIBL007CL) SRCFILE(XXX/SOURCE) + */
/* TEXT('CPP for SAVLIBL command') */
/* */
/*===================================================================*/

PGM

DCL VAR(&CURLIB) TYPE(*CHAR) LEN(10)
DCL VAR(&DTAQE) TYPE(*CHAR) LEN(300)
DCL VAR(&DTAQELEN) TYPE(*DEC) LEN(5) VALUE(300)
DCL VAR(&USRLIBL) TYPE(*CHAR) LEN(275)

MONMSG MSGID(CPF0000 MCH0000) EXEC(GOTO CMDLBL(ERROR))

/* Create library list stack if necessary */
CHKOBJ OBJ(QTEMP/LIBLSTACK) OBJTYPE(*DTAQ)
MONMSG MSGID(CPF9801) EXEC(DO)

RCVMSG MSGTYPE(*LAST) RMV(*YES)
CRTDTAQ DTAQ(QTEMP/LIBLSTACK) TYPE(*STD) MAXLEN(300) +

SEQ(*LIFO) TEXT('Library list stack')
ENDDO

/* Save library list into stack */
RTVJOBA USRLIBL(&USRLIBL) CURLIB(&CURLIB)
IF COND(&CURLIB *EQ '*NONE') THEN(DO)
CHGVAR VAR(&CURLIB) VALUE('*CRTDFT')
ENDDO

CHGVAR VAR(&DTAQE) VALUE(&CURLIB *CAT &USRLIBL)

CALL PGM(QSNDDTAQ) PARM('LIBLSTACK' 'QTEMP' +

&DTAQELEN &DTAQE)

RETURN

ERROR:

FWDPGMMSG
MONMSG MSGID(CPF0000)

ENDPGM /*===================================================================*/

Figure 7: CL program LIBL007CL

 /*===================================================================*/ /* To compile: */ /* */ /* CRTCLPGM PGM(XXX/LIBL007CL) SRCFILE(XXX/SOURCE) + */ /* TEXT('CPP for SAVLIBL command') */ /* */ /*===================================================================*/ PGM 

DCL VAR(&CURLIB) TYPE(*CHAR) LEN(10)   DCL VAR(&DTAQE) TYPE(*CHAR) LEN(300)   DCL VAR(&DTAQELEN) TYPE(*DEC) LEN(5) VALUE(300)   DCL VAR(&USRLIBL) TYPE(*CHAR) LEN(275)

MONMSG MSGID(CPF0000 MCH0000) EXEC(GOTO CMDLBL(ERROR))

/* Create library list stack if necessary */   CHKOBJ OBJ(QTEMP/LIBLSTACK) OBJTYPE(*DTAQ)   MONMSG MSGID(CPF9801) EXEC(DO)     RCVMSG MSGTYPE(*LAST) RMV(*YES)     CRTDTAQ DTAQ(QTEMP/LIBLSTACK) TYPE(*STD) MAXLEN(300) +                  SEQ(*LIFO) TEXT('Library list stack')   ENDDO

/* Save library list into stack */   RTVJOBA USRLIBL(&USRLIBL) CURLIB(&CURLIB)   IF COND(&CURLIB *EQ '*NONE') THEN(DO)     CHGVAR VAR(&CURLIB) VALUE('*CRTDFT')   ENDDO

CHGVAR VAR(&DTAQE) VALUE(&CURLIB *CAT &USRLIBL)

CALL PGM(QSNDDTAQ) PARM('LIBLSTACK' 'QTEMP' +                &DTAQELEN &DTAQE)

RETURN

ERROR:   FWDPGMMSG   MONMSG MSGID(CPF0000)

ENDPGM

Figure 8: Command RSTLIBL

/* */
/* CRTCMD CMD(XXX/RSTLIBL) PGM(XXX/LIBL008CL) + */
/* SRCFILE(XXX/SOURCE) TEXT('Restore Library +*/
/* List') */
/* */
/*===================================================================*/

CMD PROMPT('Restore Library List') /*===================================================================*/

/* To compile: */
/* */
/* CRTCLPGM PGM(XXX/LIBL008CL) SRCFILE(XXX/SOURCE) + */
/* TEXT('CPP for RSTLIBL command') */
/* */
/*===================================================================*/

PGM

DCL VAR(&CMD) TYPE(*CHAR) LEN(300)
DCL VAR(&CMDLEN) TYPE(*DEC) LEN(15 5) VALUE(300)
DCL VAR(&CURLIB) TYPE(*CHAR) LEN(10)

DCL VAR(&DTAQE) TYPE(*CHAR) LEN(300)
DCL VAR(&DTAQELEN) TYPE(*DEC) LEN(5) VALUE(300)
DCL VAR(&USRLIBL) TYPE(*CHAR) LEN(275)

DCL VAR(&WAIT) TYPE(*DEC) LEN(5) VALUE(0)

MONMSG MSGID(CPF0000 MCH0000) EXEC(GOTO CMDLBL(ERROR))

/* Reject request if SAVLIBL not executed before */
CHKOBJ OBJ(QTEMP/LIBLSTACK) OBJTYPE(*DTAQ)
MONMSG MSGID(CPF9801) EXEC(DO)

SNDPGMMSG MSGID(CPF9898) MSGF(QCPFMSG) MSGDTA('RSTLIBL +
not allowed before SAVLIBL') MSGTYPE(*ESCAPE)
ENDDO

/* Restore library list */
CALL PGM(QRCVDTAQ) PARM('LIBLSTACK' 'QTEMP' +

&DTAQELEN &DTAQE &WAIT)

/* Reject request if nothing to restore */
IF COND(&DTAQE *EQ ' ') THEN(DO)

SNDPGMMSG MSGID(CPF9898) MSGF(QCPFMSG) MSGDTA('Library +
list stack is empty') MSGTYPE(*ESCAPE)
ENDDO

CHGVAR VAR(&CURLIB) VALUE(%SST(&DTAQE 1 10))
CHGVAR VAR(&USRLIBL) VALUE(%SST(&DTAQE 11 275))

CHGCURLIB CURLIB(&CURLIB)
CHGVAR VAR(&CMD) VALUE('CHGLIBL (' *BCAT &USRLIBL +

*TCAT ')')
CALL PGM(QCMDEXC) PARM(&CMD &CMDLEN)

RETURN

ERROR:

FWDPGMMSG
MONMSG MSGID(CPF0000)

ENDPGM

Figure 10: Using SAVLIBL and RSTLIBL

PGM

/* Save library list at this point */
SAVLIBL

/* Modify library list as needed */
ADDLIBLE ...

RMVLIBLE ...
CHGCURLIB ...

/* Do other tasks */

Figure 9: CL program LIBL008CL

...

CALL pgm1 /* Program may use SAVLIBL and RSTLIBL too */
...

/* Restore library list */
RSTLIBL

/* Continue processing */

ENDPGM

BLOG COMMENTS POWERED BY DISQUS

LATEST COMMENTS

Support MC Press Online

$

Book Reviews

Resource Center

  • SB Profound WC 5536 Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application. You can find Part 1 here. In Part 2 of our free Node.js Webinar Series, Brian May teaches you the different tooling options available for writing code, debugging, and using Git for version control. Brian will briefly discuss the different tools available, and demonstrate his preferred setup for Node development on IBM i or any platform. Attend this webinar to learn:

  • SB Profound WP 5539More than ever, there is a demand for IT to deliver innovation. Your IBM i has been an essential part of your business operations for years. However, your organization may struggle to maintain the current system and implement new projects. The thousands of customers we've worked with and surveyed state that expectations regarding the digital footprint and vision of the company are not aligned with the current IT environment.

  • SB HelpSystems ROBOT Generic IBM announced the E1080 servers using the latest Power10 processor in September 2021. The most powerful processor from IBM to date, Power10 is designed to handle the demands of doing business in today’s high-tech atmosphere, including running cloud applications, supporting big data, and managing AI workloads. But what does Power10 mean for your data center? In this recorded webinar, IBMers Dan Sundt and Dylan Boday join IBM Power Champion Tom Huntington for a discussion on why Power10 technology is the right strategic investment if you run IBM i, AIX, or Linux. In this action-packed hour, Tom will share trends from the IBM i and AIX user communities while Dan and Dylan dive into the tech specs for key hardware, including:

  • Magic MarkTRY the one package that solves all your document design and printing challenges on all your platforms. Produce bar code labels, electronic forms, ad hoc reports, and RFID tags – without programming! MarkMagic is the only document design and print solution that combines report writing, WYSIWYG label and forms design, and conditional printing in one integrated product. Make sure your data survives when catastrophe hits. Request your trial now!  Request Now.

  • SB HelpSystems ROBOT GenericForms of ransomware has been around for over 30 years, and with more and more organizations suffering attacks each year, it continues to endure. What has made ransomware such a durable threat and what is the best way to combat it? In order to prevent ransomware, organizations must first understand how it works.

  • SB HelpSystems ROBOT GenericIT security is a top priority for businesses around the world, but most IBM i pros don’t know where to begin—and most cybersecurity experts don’t know IBM i. In this session, Robin Tatam explores the business impact of lax IBM i security, the top vulnerabilities putting IBM i at risk, and the steps you can take to protect your organization. If you’re looking to avoid unexpected downtime or corrupted data, you don’t want to miss this session.

  • SB HelpSystems ROBOT GenericCan you trust all of your users all of the time? A typical end user receives 16 malicious emails each month, but only 17 percent of these phishing campaigns are reported to IT. Once an attack is underway, most organizations won’t discover the breach until six months later. A staggering amount of damage can occur in that time. Despite these risks, 93 percent of organizations are leaving their IBM i systems vulnerable to cybercrime. In this on-demand webinar, IBM i security experts Robin Tatam and Sandi Moore will reveal:

  • FORTRA Disaster protection is vital to every business. Yet, it often consists of patched together procedures that are prone to error. From automatic backups to data encryption to media management, Robot automates the routine (yet often complex) tasks of iSeries backup and recovery, saving you time and money and making the process safer and more reliable. Automate your backups with the Robot Backup and Recovery Solution. Key features include:

  • FORTRAManaging messages on your IBM i can be more than a full-time job if you have to do it manually. Messages need a response and resources must be monitored—often over multiple systems and across platforms. How can you be sure you won’t miss important system events? Automate your message center with the Robot Message Management Solution. Key features include:

  • FORTRAThe thought of printing, distributing, and storing iSeries reports manually may reduce you to tears. Paper and labor costs associated with report generation can spiral out of control. Mountains of paper threaten to swamp your files. Robot automates report bursting, distribution, bundling, and archiving, and offers secure, selective online report viewing. Manage your reports with the Robot Report Management Solution. Key features include:

  • FORTRAFor over 30 years, Robot has been a leader in systems management for IBM i. With batch job creation and scheduling at its core, the Robot Job Scheduling Solution reduces the opportunity for human error and helps you maintain service levels, automating even the biggest, most complex runbooks. Manage your job schedule with the Robot Job Scheduling Solution. Key features include:

  • LANSA Business users want new applications now. Market and regulatory pressures require faster application updates and delivery into production. Your IBM i developers may be approaching retirement, and you see no sure way to fill their positions with experienced developers. In addition, you may be caught between maintaining your existing applications and the uncertainty of moving to something new.

  • LANSAWhen it comes to creating your business applications, there are hundreds of coding platforms and programming languages to choose from. These options range from very complex traditional programming languages to Low-Code platforms where sometimes no traditional coding experience is needed. Download our whitepaper, The Power of Writing Code in a Low-Code Solution, and:

  • LANSASupply Chain is becoming increasingly complex and unpredictable. From raw materials for manufacturing to food supply chains, the journey from source to production to delivery to consumers is marred with inefficiencies, manual processes, shortages, recalls, counterfeits, and scandals. In this webinar, we discuss how:

  • The MC Resource Centers bring you the widest selection of white papers, trial software, and on-demand webcasts for you to choose from. >> Review the list of White Papers, Trial Software or On-Demand Webcast at the MC Press Resource Center. >> Add the items to yru Cart and complet he checkout process and submit

  • Profound Logic Have you been wondering about Node.js? Our free Node.js Webinar Series takes you from total beginner to creating a fully-functional IBM i Node.js business application.

  • SB Profound WC 5536Join us for this hour-long webcast that will explore:

  • Fortra IT managers hoping to find new IBM i talent are discovering that the pool of experienced RPG programmers and operators or administrators with intimate knowledge of the operating system and the applications that run on it is small. This begs the question: How will you manage the platform that supports such a big part of your business? This guide offers strategies and software suggestions to help you plan IT staffing and resources and smooth the transition after your AS/400 talent retires. Read on to learn: