可变长度表中的内存分配

发布于 2024-08-17 10:08:27 字数 1064 浏览 4 评论 0原文

假设我在 WORKING-STORAGE 中定义了以下可变长度表...

01  SOAP-RECORD.                                           
    05  SOAP-INPUT        PIC X(8)          VALUE SPACES.
    05  SOAP-STATUS       PIC 9             VALUE ZERO.                         
    05  SOAP-MESSAGE      PIC X(50)         VALUE SPACES.
    05  SOAP-ITEMS        OCCURS 0 TO 500 TIMES   
                          DEPENDING ON ITEM-COUNT
                          INDEXED BY ITEM-X.     
        10 SI-SUB-ITEMS   OCCURS 0 TO 100 TIMES
                          DEPENDING ON SUB-COUNT
                          INDEXED BY SUB-X.     
           15 SS-KEY      PIC X(8)          VALUE SPACES.
           15 SS-AMOUNT   PIC -9(7).99      VALUE ZEROS.
           15 SS-DESCR    PIC x(100)        VALUE SPACES.

当该程序运行时，它最初会分配该表可能需要的空间，还是分配更加动态记忆？我猜想 DEPENDING ON 子句会使其更加动态，因为随着 ITEM-COUNT 变量的增加，它会分配更多内存。一位同事告诉我情况并非如此，但他并不能 100% 确定。所以我真的很想知道它是如何工作的，以便尽可能有效地构建我的程序。

PS：是的，我正在编写一个新的 COBOL 程序！它实际上是一个 CICS Web 服务。我不认为这种语言会消亡:(

原文

Say I have the following variable-length table defined in WORKING-STORAGE...

01  SOAP-RECORD.                                           
    05  SOAP-INPUT        PIC X(8)          VALUE SPACES.
    05  SOAP-STATUS       PIC 9             VALUE ZERO.                         
    05  SOAP-MESSAGE      PIC X(50)         VALUE SPACES.
    05  SOAP-ITEMS        OCCURS 0 TO 500 TIMES   
                          DEPENDING ON ITEM-COUNT
                          INDEXED BY ITEM-X.     
        10 SI-SUB-ITEMS   OCCURS 0 TO 100 TIMES
                          DEPENDING ON SUB-COUNT
                          INDEXED BY SUB-X.     
           15 SS-KEY      PIC X(8)          VALUE SPACES.
           15 SS-AMOUNT   PIC -9(7).99      VALUE ZEROS.
           15 SS-DESCR    PIC x(100)        VALUE SPACES.

When this program runs, will it initially allocate as much space as this table could possibly need, or is it more dynamic about allocating memory? I would guess that the DEPENDING ON clause would make it more dynamic in the sense that it would allocate more memory as the ITEM-COUNT variable is incremented. A co-worker tells me otherwise, but he is not 100% sure. So I would really like to know how this works in order to structure my program as efficiently as possible.

PS: Yes, I am writing a new COBOL program! It's actually a CICS web service. I don't think this language will ever die :(

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清风不识月 2024-08-24 10:08:27

您没有提及您正在使用哪个编译器，但是，至少在当前的 2002 COBOL 标准之前，为 OCCURS...DEPENDING ON (ODO) 数据项分配的空间不需要是动态的。（实际上，数据项的变化只是出现的次数，而不是长度。）尽管您的编译器供应商可能已经实现了标准的扩展，但我不知道有任何供应商在该领域这样做了。

该标准的下一个（但尚未批准）修订包括对具有新 OCCURS DYNAMIC 格式的动态容量表的支持。

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别靠近我心 2024-08-24 10:08:27

在 CICS 世界中，OCCURS DEPENDING ON (ODO) 可用于创建
在运行时动态调整大小的表。但是，您声明的方式
SOAP-RECORD 将分配足够的内存来保存最大大小的记录。

请尝试以下操作：

首先，将 SOAP-RECORD 移至 LINKAGE SECTION 中。申报物品
在链接部分没有为它们分配任何内存。在此
点你只有一个记录布局。留下声明
WORKING-STORAGE 中的 ITEM-COUNT 和 SUB-COUNT。

接下来，在 WORKING-STORAGE 中声明一个指针和长度，如下所示：

77 SOAP-PTR       USAGE POINTER.
77 SOAP-LENGTH    PIC S9(8) BINARY.

最后在 PROCEDURE DIVISION 中：设置数组的大小
一些实际值的尺寸；分配
适当数量的内存，然后将两者连接起来。例如：

MOVE 200 TO ITEM-COUNT
MOVE 15 TO SUB-COUNT
MOVE LENGTH OF SOAP-RECORD TO SOAP-LENGTH
EXEC CICS GETMAIN
     BELOW
     USERDATAKEY
     SET(SOAP-PTR)
     FLENGTH(SOAP-LENGTH)
END-EXEC
SET ADDRESS OF SOAP-RECORD TO SOAP-PTR

这将仅分配足够的内存来存储包含 200 个 SOAP-ITEMS 的 SOAP-RECORD
每个包含 15 个 SI-SUB-ITEMS。

请注意，LENGTH OF 寄存器为您提供了 SOAP-RECORD 的大小
基于 ODO 对象值（ITEM-COUNT、SUB-COUNT）而不是
发生的最大数量。

非常重要...完成后不要忘记释放内存！

In the CICS world, OCCURS DEPENDING ON (ODO) can be used to create a
table that is dynamically sized at run time. However, the way you are declaring
SOAP-RECORD will allocate enough memory to hold a record of maximum size.

Try the following:

First, move the SOAP-RECORD into LINKAGE SECTION. Items declared
in the linkage section do not have any memory allocated for them. At this
point you only have a record layout. Leave the declaration of
ITEM-COUNT and SUB-COUNT in WORKING-STORAGE.

Next, declare a pointer and a length in WORKING-STORAGE something like:

77 SOAP-PTR       USAGE POINTER.
77 SOAP-LENGTH    PIC S9(8) BINARY.

Finally in the PROCEDURE DIVISION: Set the size of the array
dimensions to some real values; allocate the
appropriate amount of memory and then connect the two. For example:

MOVE 200 TO ITEM-COUNT
MOVE 15 TO SUB-COUNT
MOVE LENGTH OF SOAP-RECORD TO SOAP-LENGTH
EXEC CICS GETMAIN
     BELOW
     USERDATAKEY
     SET(SOAP-PTR)
     FLENGTH(SOAP-LENGTH)
END-EXEC
SET ADDRESS OF SOAP-RECORD TO SOAP-PTR

This will allocate only enough memory to store a SOAP-RECORD with 200 SOAP-ITEMS
each of which contain 15 SI-SUB-ITEMS.

Note that the LENGTH OF register gives you the size of SOAP-RECORD
based on the ODO object values (ITEM-COUNT, SUB-COUNT) as opposed to
the maximum number of OCCURS.

Very important... Don't forget to deallocate the memory when your done!

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