Thank you for assistance, I hope, finally I will be able to solve a problem.
What do you mean about puzzling 1 and 2?
1. If S1 saved into external file with m extention (filename.m), it is not possible to read it by read operator. In other words, read returns nothing. Any other extention allows to save and read S1 as needed.
2. Assuming with subs indeed is more simple, now I use this workaround.
Next, I see, that it is necessary to use output = array for correct saving of solution. But I have to calculate integrals on z(x) and z'(x); besides, the second derivatives of solution (z''(x)) are incorporated into right part of ODE, which I solve later. If z(x) and z'(x) are procedures, I can find z''(x) from initial ODE and fulfill all calculations, But if z(x) and z'(x) are presented by arrays, I should write special procedure for numerical integration of such functions (presented by a set of points). It is desirable to avoid this.
BTW, I have the same configuration (M 18.02, W 7 x86 Ult).