Welcome to the IBM Rational PL/I community. Here you will find the latest technical and business information, and educational information about PL/I and related z/OS and AIX topics including IMS, CICS, and Rational Developer for System z.
One of the new options introduced in the new 4.2 release of Enterprise PL/I
is the UNROL L option. However, to understand it, you first need to understand
what the compiler does with loops.
Usually, the compiler turns a DO loop into a sequence of instructions which is
followed by a test and then a conditional branch back to repeat those instructions
with some updated values (and the sequence of instructions may be preceded by a
conditional test to see if the loop should be run at all).
FREE newsletter - get IBM Software news, special #PowerSystems features - subscribe: http ://b it.l y/rs 1rZn #POWER7 We just published a special Power Systems Edition of the newsletter, which you can see here - http ://w ww-1 48.i bm.c om/t ela/ webm ail/ NlDy nami cPag e/95 40/3 2113 /cos meti c?we b_pa ge_i d=54 6427 & pre=0 - and we're also including Power Systems-related content in each monthly issue.
Check out all the information about the latest release of Enterprise PL/I for z/OS. You can
get a summary of the release as well as all the announcement details.
See what's new with Enterprise PL/I for z/OS, V4.2 including enhancements to leverage the latest z/OS. For all the details about the Enterprise PL/I for z/OS, V4.2 announcement, see I BM Enterprise PL/I for z/OS V4.2 delivers performance improvements and usability enhancements.
Under the old OS PL/I and PL/I for MVS compilers, all extents (i.e. bounds and string lengths) for STATIC variables
and for BASED variables (not using REFER) had to be optionally signed integers. This made it hard to parameterize your
code (unless you used the macro preprocessor and then your listing would look much different than your source).
With Enterprise PL/I however, extents are required only to be what are known as "restricted expressions", i.e. expressions
that the compiler can reduce to a... [More]
Code reviews were once common practice, but at some companies they have been reduced or even eliminated entirely. Often this
has been done in the name of cost savings even though the earlier a bug is found in the application life cycle, the less it costs.
Also, if you are still conducting code reviews, your coworkers are probably not perfect: they can miss
some errors and can overlook violations of your coding standards .
Fortunately, the Enterprise PL/I compiler can help you... [More]
There are three, perhaps overlooked, new features of Enterprise that let you "compile out" code either
unconditionally or conditionally:
To cause the compiler to skip some code unconditionally, you could try to enclose it in comments. But this works
only if that code itself contains no comments. However, as of the 3.9 release, you can enclose code
in %DO SKIP; ... %END; , and then the compiler will unconditionally skip over the enclosed code.
To cause the compiler to... [More]
There are many good things about the new PLI for AIX 3.1 release, but the biggest is that
PL/I for AIX is now fully up-to-date: it had been stuck at its last release in 2004, but
it now has all the language features added to Enterprise PL/I (and PL/I for Windows) in the
years since then.
Recent blog entries point to documents with all the details of what's in the 3.1 release,
but in brief, PL/I for AIX, Enterprise PL/I, and PL/I for Windows
support the same compiler options
Check out all the information about the latest release of PL/I for AIX. You can get a summary of the release as well as all the announcement details. See what's new with PL/I for AIX V3.1 including enhancements to leverage the latest POWER7 hardware and interoperability with the latest middleware. For all the details about the PL/I for AIX, V3.1 announcement, see IBM PL/I for AIX , V3.1 delivers support for the latest IBM POWER7 Systems architecture as well as many functional improvements and usability enhancements .
Want to experience PL/I for AIX, productive and powerful development environment for building PL/I applications. Check out these features in PL/I for AIX, V3.1: Provides improved performance via both front-end changes and back-end optimizer enhancements Provides an improved debugger that enables you to conveniently debug programs form your windows-based workstation Improves the MACRO preprocessor Provides improved support for SQL and CICS Leverages productivity with new and improved built-in functions Increases quality control with new and... [More]
The history of PL/I stretches back to the 1970s when IBM, at the prompting of the SHARE user group, delivered the first PL/I compiler so that users would have a language with the combined strengths of Fortran and COBOL. IBM then delivered three releases of OS PL/I Version 2 in the 1980s and PL/I for MVS and VM in the early 1990s. All of these releases were based on a common code base that gradually became old, plus both hard and expensive to enhance and maintain.
However, with the advent of the PC, IBM built a... [More]
Do you want to prove the depth of your PL/I knowledge to a prospective employer? Or do you
want to verify the PL/I skills of a company to whom you might outsource your PL/I code?
The PL/I certification , developed jointly by IBM and representatives from PL/I
companies from Europe and the US, can help with these and similar tasks.
IBM PL/I professional certification
site you will find that there are two certification levels for PL/I: one for the general PL/I... [More]
If you use the TEST option and DebugTool, Enterprise PL/I will show you the source as you coded it.
So, for example, if you have code that contains an EXEC SQL statement, you will see in the
debugger just that EXEC SQL statement as you coded it and not the many, many statements generated by the
preprocessor and visible in the listing. This is a big plus since those generated
statements will be largely meaningless to you and would certainly not be ones
you should be debugging and fixing.
In PL/I conversions, BINARY rules over DECIMAL, and FLOAT, over FIXED.
This means, for example, that when an expression contains a BINARY and a DECIMAL operand, then
the result will be BINARY.
Hence, for the assignment in this code
dcl a fixed bin;
dcl b float dec;
b = b + a ;
there will be these conversions
a will be converted to FLOAT BIN
b will be converted... [More]
For many years, the only floating point representation on z/OS was hexadecimal float. This is a base 16 representation, but most of us have 10 fingers and most business applications want to perform decimal calculations.
The difference between these 2 bases leads to problems as exemplified by this code:
dcl f1 float dec(6);
dcl f2 fixed dec(5,3);
dcl f3 float dec(6);
f1 = 4;
f2 = f1 / 100e0;
put skip data( f2 );
PL/I has complex rules for how structures are mapped and for when padding is inserted.
However, it can be important to know when there is padding in a structure (for example,
if you pass that structure to a program compiled by a language, such as C or COBOL,
that may map the structure differently).
With Enterprise PL/I 4.1, if you specify the new NOPADDING suboption to the compiler's
RULES option, the compiler will issue an E-level message for any structure that contains
RULES(NOPADDING) is... [More]
Enterprise PL/I has always supported "named constants", i.e. scalars declared with the VALUE attribute, which make your
code more maintainable than using the constants as is, but which also allow the compiler to produce much better code
than scalars declared with the INITIAL attribute.
With Enterprise 4.1 (actually even with 3.9 although it was not documented then), you can now declare named constants in
structures (as long as all the leaf elements of such a structure have the VALUE attribute and as long... [More]
Code that uses elements of structures with multiple REFERs can be very expensive : each reference uses one or more
costly library call to remap the structure. Many PL/I users have long known that the of multiple REFERs created a
black hole for performance.
Now, with Enterprise for z/OS 4.1, for structures where all the elements are byte-aligned, those calls will be avoided and
straightforward inline code generated (because if all elements are byte-aligned, no padding is possible and thus the
address calculations are... [More]