When you execute a php script which uses odbc_exec for more than 946 times (milage may vary), the following error message is returned:

Warning - SQL error: [IBM][CLI Driver][DB2/6000] SQL0954C  Not enough storage is available in the application heap to process the statement.  SQLSTATE=57011

The following information is discovered in IBM DB2 CLI manual:

SQL_ATTR_CURSOR_TYPE (DB2 CLI v2) 
A 32-bit integer value that specifies the cursor type. The supported values are: 

SQL_CURSOR_FORWARD_ONLY = The cursor only scrolls forward. 
SQL_CURSOR_STATIC = The data in the result set is static. This is the default. 
SQL_CURSOR_KEYSET_DRIVEN = DB2 CLI supports a pure keyset cursor. The SQL_KEYSET_SIZE statement attribute is ignored. To limit the size of the keyset the application must limit the size of the result set by setting the SQL_ATTR_MAX_ROWS attribute to a value other than 0. 
This option cannot be specified for an open cursor. 

If the specified cursor type is not supported by the data source, CLI substitutes a different cursor type and returns SQLSTATE 01S02 (Option value changed). For a mixed or dynamic cursor, CLI substitutes, in order, a keyset-driven or static cursor. 

Note: The following value has also been defined by ODBC, but is not supported by DB2 CLI: 
SQL_CURSOR_DYNAMIC 
If this values is used, DB2 CLI sets the statement attribute to SQL_CURSOR_STATIC SQL_CURSOR_FORWARD_ONLY and returns SQLSTATE 01S02 (Option value changed). In this case the application should call SQLGetStmtAttr() to query the actual value. 
 
The quick work around is to edit ext/odbc/php_odbc.c, and disable SQL_CURSOR_DYNAMIC, and to change all instances of SQL_CURSOR_DYNAMIC to SQL_CURSOR_FORWARD_ONLY.  It appear that DB2/CLI exhibits memory leak when statement type is set to SQL_CURSOR_DYNAMIC.

The diff follows:

--- php_odbc.c.orig     Thu Dec 21 00:44:49 2000
+++ php_odbc.c  Thu Dec 21 01:00:30 2000
@@ -354,7 +354,9 @@
        REGISTER_LONG_CONSTANT("SQL_CURSOR_TYPE", SQL_CURSOR_TYPE, CONST_PERSISTENT | CONST_CS);
        REGISTER_LONG_CONSTANT("SQL_CURSOR_FORWARD_ONLY", SQL_CURSOR_FORWARD_ONLY, CONST_PERSISTENT | CO
NST_CS);
        REGISTER_LONG_CONSTANT("SQL_CURSOR_KEYSET_DRIVEN", SQL_CURSOR_KEYSET_DRIVEN, CONST_PERSISTENT | 
CONST_CS);
+#ifndef HAVE_IBMDB2
        REGISTER_LONG_CONSTANT("SQL_CURSOR_DYNAMIC", SQL_CURSOR_DYNAMIC, CONST_PERSISTENT | CONST_CS);
+#endif
        REGISTER_LONG_CONSTANT("SQL_CURSOR_STATIC", SQL_CURSOR_STATIC, CONST_PERSISTENT | CONST_CS);
        
        REGISTER_LONG_CONSTANT("SQL_KEYSET_SIZE", SQL_KEYSET_SIZE, CONST_PERSISTENT | CONST_CS);
@@ -758,7 +760,11 @@
                        /* Try to set CURSOR_TYPE to dynamic. Driver will replace this with other
                           type if not possible.
                        */
+#ifdef HAVE_IBMDB2
+                       if (SQLSetStmtOption(result->stmt, SQL_CURSOR_TYPE, SQL_CURSOR_FORWARD_ONLY)
+#else
                        if (SQLSetStmtOption(result->stmt, SQL_CURSOR_TYPE, SQL_CURSOR_DYNAMIC)
+#endif
                                == SQL_ERROR) {
                                odbc_sql_error(conn->henv, conn->hdbc, result->stmt, " SQLSetStmtOption"
);
                                SQLFreeStmt(result->stmt, SQL_DROP);
@@ -1085,7 +1091,11 @@
                        /* Try to set CURSOR_TYPE to dynamic. Driver will replace this with other
                           type if not possible.
                         */
+#ifdef HAVE_IBMDB2
+                       if (SQLSetStmtOption(result->stmt, SQL_CURSOR_TYPE, SQL_CURSOR_FORWARD_ONLY)
+#else
                        if (SQLSetStmtOption(result->stmt, SQL_CURSOR_TYPE, SQL_CURSOR_DYNAMIC)
+#endif
                                == SQL_ERROR) {
                                odbc_sql_error(conn->henv, conn->hdbc, result->stmt, " SQLSetStmtOption"
);
                                SQLFreeStmt(result->stmt, SQL_DROP);