Level 77 in COBOL/400

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COBOL
COBOL/400
what is the significance of level 77 in COBOL/400

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In the current version of COBOL is none. In the older versions, the compiler handled 77 level as a single value and the “01″ as possible subdivided field.

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Level 01 and Level 77 items are aligned on word boundaries. But I seem to remember (way back when) that Level 77 items could not be stomped on by accident. And I think nowdays that point is moot.

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Level Number 77 in COBOL/400.

1. The Level number 77 cannot be subdivided into other items. This is considered to be an elementary item. Also, it must begin in AREA A.

2. Also, Level Number 77 is used for LIKE Clause. For LIKE Clause, we can specify the level number from 1-49 or 77.

Sample Code: 01 FIELD1 PIC X(5) VALUE IS ‘ABC’.
77 FIELD2 LIKE FIELD1 VALUE ‘BCD’.

Hope this helps.

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  • abhisheka1
    to declare Standalone fields
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  • Miville
    Un to the advent of micro-computers and stack-based execution micro-programming, and especially in the olden days when cpu time was as dear as gold and the compilers not yet equipped with perfected post-assembly optimization methods, the critical factor for object-code speed was register allocation, i.e., which frequently-used variables were to be associated with quick-access registers and short-format machine instructions rather than with regular core and long-format instructions.  The 77-level data items represented each of them in order of priority (the most frequently referred to by executing code) the variables to be associated with the quick-access registers (there used to be 16 with IBM 360).  Early Fortran used to have a now defunct command called FREQUENCY to the same effect.  COBOL retained the concept longer since among the high-level languages it strove the best to mirror nevertheless the machine code to produce (especially as regards the DATA division that makes COBOL one of the last languages to allow byte-wise work in the core and in the file buffers), as a manual transmission truck in the world of automatic transmission cars.  You used to put your most used counters at the 77-level to better your benchmark and the little-used variables within more distant structures beginning at 01 level, in the working-storage proper where all fields were contiguously organized as they appeared in the code, whereas at the 77 level the compiler chose their place. From the seventies onwards, newer programs of code optimization shared by most languages and compilers, and then wholly new computer architecture based on stacks rather than on register allocation reduced the 77-level feature to a mere historical curiosity maintained by routine and tradition.
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